Resin roller and device and method for manufacturing the resin roller

ABSTRACT

A resin roller ( 10 ) is produced by disposing a core body ( 21 ) in a forming metal mold ( 1 ) having a cylindrical metal mold ( 13 ) and core supporting members ( 14 ) furnished at both edge parts of the cylindrical metal mold ( 13 ) as well as causing the core supporting members ( 14 ) to hold the both edge parts, and pouring a forming resin into the metal mold and solidifying it. The resin roller ( 10 ) has the core body ( 21 ) of the same outer diameter over a full length and a cylindrical resin-formed body ( 12 ), sealing members ( 24, 26 ) are furnished around the core body ( 21 ) in the vicinity of both edge parts of the resin-formed body ( 12 ), and the core body is disposed such that the sealing members ( 24, 26 ) contact edge faces ( 14   a ) at sides of a roller forming space of the core supporting members ( 14 ).

TECHNICAL FIELD

The present invention relates to a resin roller such as a filmdeveloping roller, an electrically charging roller, or a transcribingroller to be incorporated into various kinds of devices employing anelectrophotographic system of a laser printer, copier or facsimileapparatus. Further, the present invention relates to an apparatus ofproducing the resin roller. Still further, the invention relates to aninjection molding apparatus of the resin roller as well as a formingmetal mold.

TECHNICAL BACKGROUND

Many kinds of devices employing electrophotographic systems of a laserprinter, copier or facsimile apparatus are incorporated with a rollersuch as a film developing roller, an electrically charging roller, or atranscribing roller. One example of these rollers is shown in FIG. 24.

A roller 10 has a core body 21 and a cylindrical forming body 12fabricated with a resin. A metal mold for forming the roller 10 has, asshown in for example FIG. 25, a cylindrical metal mold 13 and coresupporting members 14 located at upper and lower both edges of thecylindrical metal mold 13 for supporting a core 21 inserted inside ofthe cylindrical metal mold 13 and sealing both edges of the cylindricalmetal mold 13. The lower core supporting member 14 is defined with aresin injecting inlet 16 for injecting a resin material into a rollerforming space 15, while the resin injecting inlet 16 is urged outside ofthe metal mold with a resin injecting nozzle 18 of a forming machinefrom a semi-circular nozzle touch portion 19, so that the resin materialis introduced into the roller forming 15.

After completion of filling the resin into the metal mold, the resin inthe roller forming space 15 is hot-set. Hot-setting the resin, the coresupporting members 14 are removed upward and downward respectively alongan axial direction from the cylindrical metal mold 13. Subsequently, thecore body 21 is extruded from the cylindrical metal mold 13 to take outa formed product (roller) held within the cylindrical metal mold 13.

The core supporting member 14 is provided with concave parts 17 forsupporting the core body 21 at edges 21 a, and in order to make easyinsertion of the edge 21 a of the core supporting member 14 into theconcave part 17 or taking variation within dimensional tolerance of theedge of the core body into consideration, spaces of 10 to 20μareprovided between the concave part 17 and the core supporting member 14.So, if the resin is poured into the metal mold at high pressure or if apressure in the mold is high when the resin is expanded at hot-setting,a defect is present that the resin leaks out of the metal mold from thespaces. The leaked resin is adhered to the edges 21 a of the core body21 or to an interior of the concave part 17 of the core supportingmember 14, and it should be removed after formed products have beenreleased from the mold.

In case the core body 21 used to the resin roller is, as shown in FIG.25, differs an outer diameter in the center part of the core body 21 andan outer diameter in the edge part 21 a of the core body 21, and theouter diameter in the center part of the core body 21 is larger thanthat of the edge part, a method is to attach sealing members 24 (forexample, O-ring) to the core supporting member 14 so as to contact sidefaces of the center part of the core body 21 for preventing the resinleakage.

However, the core body 21 being different in the outer diameters in thecenter part and in the center part thereof has disadvantages of highprocessing cost and high material cost of the core body 21, andaccordingly a cost of the core body 21 is expensive.

In order to lower the cost of the core body 21 and make thickness of anelastic layer large for aiming at reducing rubber elastic hardness ofthe formed body 12 (elastic layer), such a core body 21 is sometimesused which uses core body 21 being the same in the center part of thecore body 21 and the outer diameter in the edge part 21 a of the corebody 21.

In this case, as illustrated in FIG. 26, used is the core supportingmember 14 which is buried with sealing members 24 (for example, O-ring)opening in the concave part 17 thereof. But there is a defect that thesealing members 24 buried in the core supporting member 14 are brokenwhile repeatedly attaching the core body 21 to the concave parts 17, sothat an effect for avoiding the resin leakage is decreased.

Further, for adopting a structure of burying the sealing members in thecore supporting member 14, taking strength of burying grooves intoconsideration, it is necessary to bury the sealing members in depth ofaround 0.5 to 1 mm from the side edge face of a resin formed product ofthe core supporting member 14. Therefore, until around 0.5 to 1 mm fromthe side edge face of the resin formed product of the core supportingmember 14, the resin leakage cannot be stopped with the sealing members24, and the resin leakage 30 by the amount thereof occurs.

When using the core body 21 which is the same in the outer diameter inthe center part of the core body 21 and the outer diameter in the edgepart 21 a thereof, a problem is to shorten a life of the sealing memberand cause the resin leakage in parts from a resin formed edge part tothe sealing member.

Thus, it is indispensable to frequently exchange the sealing membersowing to the short life thereof and remove the leakage resin at edgeparts, and in turn a cost-up of the resin roller is invited.

Next, reference will be made to using methods of the roller by use of anexample of the resin roller for a photographic film developing process,referring to FIG. 27.

In various kinds of devices of the electrophotographic system, there isa system known as a photographic film developing process for visualizingelectrostatic latent images, which supplies a nonmagnetic unarydeveloper 55 on an image carrier 51 of a photosensitive body 50 ofcarrying the electrostatic latent image, adhering said developer to theelectrostatic latent image on the surface of the image carrier, andcontacting a developing resin roller 10 a to the image carrier 51.

Using the nonmagnetic unary developer 55, this system is cheap incomparison with a system supplying the magnetic developer by use of theconventional magnetic roller. In a case of using a magnetic binarydeveloper, a carrier itself has a short life, for example, it must beperiodically exchanged per 10000 or 20000 copies, taking trouble forexchanging the carrier. On the other hand, the above mentioned systemdoes not have such a defect. Further, in a case of using the magneticbinary developer, since the magnetic developer itself contains amagnetic substance near a different color, it is technically difficultto make the magnetic developer a color toner, but since the resin rollerof the invention is employed to the nonmagnetic developing system usingthe nonmagnetic developer, such a problem is absent.

Typical shapes of the resin roller are shown in FIGS. 28, 29 and 30. Theresin roller 10 a has a core body 21, a cylindrical resin layer 12 aformed with a resin around the core body 21, and a surface layer 12 bcovering the periphery of the resin layer 12 a.

A method for the resin roller 10 a to send the nonmagnetic unarydeveloper, depends on an electrically absorbing force, and since aproperty necessary as the developing roller makes the developerfrictional electrification between the developing surface and aregulating blade 52 for regulating a piling thickness of the developeron the surface of the developing roller, the developer is easily crackedowing to pressurization, and such a developing roller 10 a is servedwhich covers a soft resin layer 12 a on the core body 21 for avoidingthe developer from cracking.

The resin layer 12 a is often exposed at the surface, but forcontrolling electric charging of the developer or transferringperformance, it is provided on the surface with a thin surface layer 12b.

Further, explanation will be made to a producing method of the resinroller 10 a.

At first, a metal mold 120 for forming the resin layer 12 a of the resinroller 10 a has, as shown in for example FIG. 31, a cylindrical metalmold 13 and the core supporting members 14, 14 located at upper andlower both edges of the cylindrical metal mold 13 for supporting a core21 inserted inside of the cylindrical metal mold 13 and sealing bothedges of the cylindrical metal mold 13. The lower core supporting member14 is defined with a resin injecting inlet 16 for injecting a resinmaterial into a roller forming space 15 formed within the cylindricalmetal mold 13, while the resin injecting inlet 16 is urged outside ofthe metal mold with a resin injecting nozzle 18 of a forming machinefrom a semi-circular nozzle touch portion 19, so that the resin materialis introduced into the roller forming space 15.

After completion of filling the resin into the metal mold 120, the wholeof the mold 120 is heated to hot-set the resin in the roller formingspace 15. Hot-setting the resin, the core supporting members 14, 14 areremoved upward and downward respectively along the axial direction fromthe cylindrical metal mold 13. Subsequently, the core body 21 isextruded from the cylindrical metal mold 13 to take out a formed product(roller) 10 b held within the cylindrical metal mold 13.

After that, the resin layer 12 a of the roller main body 10 b producedby the above forming method is coated on the peripheral surface thereofwith a treated liquid mixed with a resin material through a spraymethod, a dipping method or a roll coater method, and dried to form asurface layer 12 b.

The roller main body 10 b produced by the above forming method hasswelling parts at edge parts of the resin layer 12 a as shown in FIG. 32when releasing from the metal mold. A mechanism of the swellingphenomenon at the edge is explained that the swelling is generated bythermal expansion and shrinkage owing to temperature difference betweentemperatures at pouring the resin into the metal mold 120 and afterreleasing from the mold, the amount of shrinkage in the axial directionis larger than that in the peripheral direction, and the formed resin isadhered to the core body 21. Even if the swelling part at the edge partof the resin layer 12 a is cut in round slice in the peripheraldirection, the edge part after cutting apparently swells similarly.

The cylindrical metal mold 13 and the core supporting members 14, 14have tolerances of respective parts and assembling spaces, and so-calledparting lines occur. If the spaces become large owing to such asabrasion in the respective parts when setting up the metal mold, theresin flows into the spaces and burrs are created at the edges of theresin layer 12 a as shown in FIG. 33.

The corner 74 of the resin roller 10 a is obtained by forming thesurface layer 12 b around the resin layer 12 a of the resin roller 10 ain the above mentioned method, and as shown in FIG. 34, actually thefilm thickness of a resin forming the surface layer 12 b is small.

When the resin roller 10 a contacts and slides with the image carrier asthe sensitive substance, since the corner of the resin roller 10 acontacts the periphery of the image carrier at larger force than thatexerting in the center part of the resin roller 10 a and the filmthickness of the surface layer 13 b is smaller than that in the centerpart, the surface layer 12 b of the corner of the resin roller 10 a iseasily worn, and in turn this abrasion causes the surface layer 12 b topeel off, and as a time passes, the surface layer 12 b gradually widensto peel in the surface of the resin roller 10 a.

For resolving those occasions, there is a method of uniformly machiningor polishing the surface of the resin roller prior to coating thesurface layer, but it takes many processing steps, and besides the resinlayer is soft, and in particular the corner could not be preciselymachined or polished.

Another method is to machine or polish the only corner, but some ofelastic resins such as, above all, silicone forming the resin layer haveviscosity or stickiness particular to these resins, so that processingparts are nappy or ragged, and the surface cannot be processed to besmooth. There is another available method which carries out the processof immersing or coating water or oil to the processing part of the resinroller while machining or polishing, but after processing, it is furthernecessary to remove water or oil.

Next, an apparatus of producing the roller will be explained in detail.The apparatus of producing the roller is mainly structured with, asshown in FIG. 35, for example, a cylindrical metal mold 61 and the coresupporting members 62 a, 62 a located at upper and lower both edges ofthe cylindrical metal mold 61 for supporting a core 21 inserted insideof the cylindrical metal mold 61 and sealing both edges of thecylindrical metal mold 61.

The lower core supporting member 62 b is defined with a straight resininjecting inlet 64 for injecting the resin material into a rollerforming space 63 formed within the cylindrical metal mold, while theresin injecting inlet is provided on the way with a closure mechanism 68for regulating a resin fluid. If a resin injecting nozzle (not shown) atthe side of the forming machine is urged to a nozzle touch portion 65formed to be semi-circular with a part opening toward outside of themetal mold of a resin injecting inlet 64, so that the resin material isintroduced into the roller forming space 63.

On the other hand, the upper core supporting member 62 a is defined witha straight air vent hole 66, and a closure mechanism 67 is provided ascrossing with the air vent hole 66 for closing the resin fluid.

The summary of the method of forming the roller by use of this producingapparatus is as follows.

At first, the core body 21 inserted within the cylindrical metal mold 61is held at its upper and lower edges by the upper and lower coresupporting members 62 a, 62 b, and subsequently a hot-setting liquidresin is filled into the roller forming space 63 through the resininjecting inlet 64, and on completion of filling, the closure mechanism68 in the lower core supporting member 62 b is operated to check acounter flow of the resin expanding within the cylindrical metal moldwhen hot-setting.

In contrast, the air vent hole 66 provided in the upper core supportingmember 62 a releases the closure mechanism 67 during filling the resinto exhaust the air in the roller forming space via the air vent hole 66outside of the metal mold, and on completion of filling the resin, theclosure mechanism is closed, and under this condition, the resin stayingin the roller forming space is hot-set.

On completion of hardening the resin, the core supporting members 62 a,62 b are removed upward and downward from the cylindrical metal mold 61along the axial direction, and finally a formed product held within thecylindrical metal mold 61 is taken out by extruding the core body 21with respect to the cylindrical metal mold 61. This is a method ofproducing rollers by means of this kind of the conventional apparatus.

However, the conventional roller producing apparatus and method areinvolved with many problems.

For example, in the conventional roller producing method, a metal molddevice composed of the core supporting member and the cylindrical metalmold is charged with a thermosetting resin, and then the upper and lowerclosure mechanisms are closed to make the forming space a closed space.The closed space is filled with the thermosetting resin to form anelastic layer (formed body), and at this time the resin hot-set withinthe closed metal mold is generated with cubical expansion. Since thefilled thermosetting liquid resin is non-compressive, an internalpressure within the metal mold by the cubic expanded resin isconsiderably high. A magnification of this internal pressure is normallymore than 100 kg/cm², though depending on air tightness of the closuremechanism provided in the core supporting member, and so the metal moldmust have sufficient pressure resistant strength. Accordingly, thicknessof the cylindrical metal mold is large, and load should be large forconnecting the cylindrical metal mold and the core supporting member.

If the internal pressure within the metal mold is large, the resin flowsinto the parting line between the cylindrical metal mold and coresupporting member, and this becomes a burr appearing at the rollerperipheral part, so that a secondary process as a polishing is necessaryto remove burrs. Further, the resin often leaks from the closuremechanism 68 provided in the lower core supporting member 62 b, so thata work is demanded to remove the resin adhered to the metal mold afterhaving formed to cause the working efficiency to go down.

A problem is present when taking out the formed product from the metalmold. If the internal pressure within the metal mold is large, as thesurface of the elastic layer is closely adhered to the inner surface ofthe metal mold, when releasing from the mold after completion ofhardening, resistance against releasing from the mold is still largeeven if the elastic layer is shrunk with enough cooling time, andscratches often appear on the surface of the elastic layer by releasingfrom the mold. For avoiding these occasions, the cylindrical metal moldis carried out with a fluorine coating treatment, or a plating treatmentfor heightening smoothness, but with such only measures, the moldreleasing property is not yet sufficient, and actually a mold releasingagent is coated on the inside of the metal mold per each time.

Next, referring to FIG. 36, explanation will be made to anotherconventional method of making rollers using the thermosetting liquidresin. This method comprises mixing silicone-based liquid base polymer(main agent), a cross linking agent, a catalyst and if necessary anelectrically conductive agent within a vacuum agitating-defoamingdevice, rendering this to be one liquid state, storing it in a container81, subsequently transferring a thermosetting liquid resin 82 in thecontainer 81 by use of a force feed pump 83 to an injection device 84,sending to a cylinder 86, measuring a predetermined amount, andinjecting into a cavity of a roller forming metal mold 88 via aninjecting nozzle 87, thereby to form a roller main body. Herein, acooling device 90 is necessary to normally keep cooled at about 10° C.or lower the transferring course comprising the container 81, injectingdevice 84, injecting nozzle 87 and transferring tube 89. In theillustrated example, a cooling liquid is circulated and supplied fromthe cooling device 90 through pipes 91 a, 91 b, 91 c, 91 d so as to cooleach of the parts. The cooling device is provided because if this isabsent, a bridging reaction of the thermosetting liquid resinprogresses, and the liquid resin is adhered to and solidified on theinner walls of the transferring course comprising the container 81,injecting device 84 and transferring tube 89, and obstacles transferringof the liquid resin, so that the apparatus is frequently necessarilydisassembled to clean to remarkably decrease productivity.

Since this cooling system heightens production cost, there is an attemptof adding a hardening retard agent to the liquid resin for avoiding thecost-up, and lengthening a pot life, but as a progressing risk of thebridging reaction of the liquid resin staying in the container 81 ishigh, a problem occurs in variation of quality between rollers at abeginning period of and after the injection forming.

However, in the conventional roller producing method employing the abovementioned cooling system,

-   (1) since the thermosetting liquid resin is cooled down at about    10° C. or lower and increases viscosity, an injecting pressure is    heightened to fill it into the cavity, it is necessary to design the    thickness of the roller forming metal mold to be durable against the    injecting pressure, and-   (2) if injecting the once cooled liquid resin, a problem arises that    a heating load is increased when hot-setting, and a hardening    reaction time is extended.

FIG. 37 is a schematically cross sectional view showing another exampleof the conventional injection forming apparatus (metal mold). In thesame, reference numeral 41 designates the cylindrical metal mold, 42shows the core body inserted inside of the cylindrical metal mold 41,43, 44 are the core supporting members, 45, 46 are cover members screwedinside with thread, and 47 is a pin. A sequence of forming the elasticroller by use of the injection forming metal mold is as follows. Atfirst, the cylindrical metal mold 41 is inserted with the core body 42,both edge parts 42 a, 42 b thereof are fitted in core supporting holes43 a, 44 a provided in the cylindrical metal molds 43, 44, these coresupporting members 43, 44 are engaged in the cylindrical metal mold 41,subsequently screwing cover members 45, 46 on the cylindrical metal mold41 to protect them and to form the roller forming space 48 for closingthe injection forming metal mold.

Next, an attaching hole 49 defined in the cover member 46 is attachedwith the resin injecting nozzle (not shown), the resin material isinjected and filled into the roller forming space 48 through the resininjecting inlet 44 b penetrating the core supporting member 44, anattaching hole 150 penetrating the cover member 45 is closed with a pin47 to shut a vent hole 151, and the cylindrical metal mold 41 is heatedto hot-set the resin material. Herein, as the heating means, listed aremeans contacting a heating mechanism (not shown) to an outside surfaceof the cylindrical metal mold 41, or means moving the injection formingmetal mold into a blast furnace (not shown) to heat it.

After hot-setting, the cylindrical metal mold 41 is cooled, and themetal mold is opened in a sequence reversal to the above mentioned forreleasing the formed product from the mold, and by repeating the abovementioned sequence, a new formed product is made.

However, the forming apparatus having the conventional injection formingmetal mold as mentioned above has the following problems. One of them isdifficult to automatize the steps of fitting the core supporting members43, 44 in the cylindrical metal mold 41 and mounting the cover members45, 46 by screwing in the production process, and must depend on manualoperation. For example, when screwing the cover members 45, 46 on thecylindrical metal mold 41, if a tightening load is too large, the corebody 42 receives excessive load and is easily bent, and if it is toosmall, the resin material leaks out owing to pressure of the filledresin to generate burrs in a formed product, resulting in decreasing theformability of the roller. Therefore, the tightening load should beadjusted, but automatization of this adjustment is difficult, notdepending on the manual operation, and even if the automatization ofthis kind of steps is possible, since facility investment of theautomatized mechanism is very expensive, so that it cannot cope withrecent fierce low cost competitions. In particular, in case of massproduction using the production apparatus of a plurality of rollers,this problem is remarkable and very much labor is demanded.

In addition, since the prior forming apparatus has such a complicatedstructure of the metal mold, when getting rid of the adhered andsolidified resin after hot-setting, a maintenance working for dissolvingand cleaning the roller producing apparatus is troublesome, taking muchlabor and inviting cost-up.

However, as shown in FIG. 38, when taking out the formed product fromthe cylindrical metal mold 13 upward or downward along the axialdirection, owing to friction between an outer periphery 12 e of a resinformed product 12 and an inside 13 a of the cylindrical metal mold 13,force is exerted in the axial direction between an outer periphery 21 eof the core body 21 and an inside periphery 12 f of the resin-formedbody 12, and when the formed body is extracted from the cylindricalmetal mold 13, a relative position between the core body 21 and theresin-formed body 12 often gets out of position. In particular, force isconcentrated to a part X of an edge 12 c of the resin-formed body 12 andthe core body 21 contacting, and as seen in FIG. 38B, the edge of theresin-formed body 12 and the core body 21 separate, and this portionserves as a trigger to often develop to a whole separation of theresin-formed body 12 and the core body 21. Therefore, a further methodis to coat the cylindrical metal mold 13 on the inside with a moldreleasing agent for reducing friction between the outer periphery 12 eof the resin-formed body of the product and the inside 13 a of thecylindrical metal mold, thereby lowering the shifting force exerting inthe axial direction between the outer periphery 21 e and the innerperiphery 12 f of the resin-formed body contacting the same. This methodincreases a step of coating the mold releasing agent, resulting incost-up.

Silicone based addition type liquid rubber material enabling to beliquid-injected inherently ordinarily used as the resin material forforming the elastic layer; polyether based addition type liquid rubbermaterial which hydrosilyl-hardens terminal allylated polyoxyalkylenebased polymer or terminal allylated polyolefin based polymer with polysiloxane based hardening agent; polyolefin based addition type liquidrubber material; urethane based liquid rubber material; EPDM rubberenabling to be injection-formed; millable silicone rubber; or NBR rubberare low in density of polar group contributing to the adhesion orscarcely contain the polar group, thereby to be difficult to adhere ametal made core body. Also in a case of using primer for improving theadhesion of the resin-formed body 12 to the core body 21, depending onthe coating of primer to the metal core body 21, influences of adhesionchecking substance (for example, a cutting oil) remaining on the metalcore body or variation in histories of temperature and moisture afterdrying, differences arise in a film forming property of the primercomponent or the adhesion thereof with metal, or residual degree offunctional group, so that the adhesion between the resin-formed body 12and the metal core body 21 might vary. If an injection pressure is highin the metal mold during forming, the primer on the surface of the metalcore 21 is forced out by the resin flowing and the primer does not fullydisplay effect, and even if the primer is coated, a sufficientlysatisfied adhesion cannot be obtained. Besides, of course a step ofcoating the primer is added to invite cost-up.

Thus, when taking out the formed product from the cylindrical metal mold13 upward or downward along the axial direction, owing to frictionbetween an outer periphery 12 e of a resin formed product 12 and aninside 13 a of the cylindrical metal mold 13, force is exerted in theaxial direction between an outer periphery 21 e of the core body 21 andan inside periphery 12 f of the resin-formed body 12, and a relativeposition between the core body 21 and the resin-formed body 12 oftengets out of position. There is a method of in advance coating the primerto the core 21 for heightening the adhesive strength between the core 21and the resin-formed body 12, but this method is involved with problemsof increasing a primer coating step and that the liquid rubber materialused as a resin forming material is inherently weak in the adhesiveforce with the metal core 21. Therefore, by decrease in the rate of goodproducts by getting out of a relative position between the core 21 andthe resin-formed body 12 or addition of the primer coating step, thecost-up is caused in the production of resin rollers.

Accordingly, it is an object of the invention to offer a resin rollerenabling to check resin leakage from a formed roller, though using acore body having the same outer diameter in the edge portion as a centerpart thereof.

It is another object of the invention to offer a resin roller improvingdurability in a surface layer and in turn having a long life.

It is a further object of the invention to offer a roller producingapparatus which is easy to release from a mold, obtains rollers withoutscratches or burrs, enables to use a metal mold having a structure ofthin thickness and light weight and to shorten a cooling time-beforereleasing the mold, and a method thereof.

It is a still further object of the invention to offer a rollerproducing apparatus which does not employ a cooling step of a liquidresin being a technical common knowledge in the prior art, restrainsheating load and shortens a hardening reaction time for decreasingenergy loss, is excellent in productivity and less to vary productquality, and a method thereof.

It is a yet further object of the invention to offer an apparatus ofinjection-forming rollers which largely reduces manually operatingsteps, easily accomplishes automatization of opening and closing themetal mold, lighten maintenance work, and enables to make rollers at lowcost.

It is another object of the invention to offer a resin roller whichenables to prevent peeling in a part contacting the edge faces of theresin-formed body and the core body for checking getting out of arelative position between the resin-formed body and the core body in theformed resin roller, and a forming metal mold therefor.

DISCLOSURE OF THE INVENTION

The resin roller of the invention is produced by disposing a core bodyin a forming metal mold having a cylindrical metal mold and coresupporting members furnished at both edge parts of the cylindrical metalmold as well as causing the core supporting members to hold said bothedge parts, and pouring a forming resin into the metal mold andsolidifying it, and is characterized in that the resin roller has thecore body of the same outer diameter over a full length and acylindrical resin- formed body, sealing members are furnished around thecore body in the vicinity of both edge parts of the resin-formed body,and the core body is disposed such that the sealing members contact edgefaces at sides of a roller forming space.

In another embodiment, the core body is defined with grooves forattaching E-rings and when the E-ring is attached in the groove and thecore body is disposed in the metal mold, the sealing members areprovided to the core body such that the sealing members respectivelycontact the E-ring and the edge faces of the core supporting members.

In another embodiment, the cylindrical member is attached to the corebody and when the core body is disposed in the metal mold, the sealingmembers are provided to the core body such that the sealing membersrespectively contact the cylindrical metal mold and the core supportingmembers.

In another embodiment, the sealing members are provided to the core bodyand when the core body is disposed within the metal mold, the edge facesof the sealing members contact the edge faces of the core supportingmembers.

In another embodiment, the core body is defined with grooves forattaching the sealing members, and when the core body is disposed withinthe metal mold, the sealing members are disposed such that the sealingmembers contact the edge faces of the core supporting members in thegrooves.

In another embodiment of the invention, the resin roller has the corebody of the same outer diameter over a full length and a cylindricalresin-formed body provided at the center part of the core body, and ischaracterized in that the sealing members are disposed around the corebody in the vicinity of both edges of the resin-formed body, and edgefaces of the sealing members are the same as edge faces of theresin-formed body or project.

A method of producing the resin roller according to the inventioncomprises the step of disposing the core supporting members at both edgeparts of the cylindrical metal mold and holding the core body with bothcore supporting members, and the step of pouring the forming resin intothe roller forming space formed between the cylindrical metal mold andthe core supporting members and solidifying the forming resin to form aresin-formed body around the core body, and is characterized bydisposing the sealing members around the core body in the vicinity ofthe edge parts of the resin-formed body, elastically contacting thesealing members to the sides of the roller forming space of the coresupporting members, and, under this condition, pouring the forming resininto the roller forming space.

By the way, in case a measure against the resin leakage for the coresupporting members and the core body is required to both edges of thecore body, the same sealing method is not necessarily selected.

Further, the resin roller according to the invention is characterized inthat the resin roller is formed in the roller main body by providing acylindrical resin layer around the core body, and the roller main bodyis chamfered or rounded at corners of edge parts of the resin layer, andthe resin layer is formed on the surface with a surface layer.

In an embodiment, the hardness of the resin layer is 25° or lower(JIS-A).

In another embodiment, a dimension of the part for chamfering orrounding the corner of the resin layer is 1 to 40 times of a swellingamount of the edge part having a larger diameter than the center part ofthe formed roller main body.

A method of producing the resin roller according to the invention ischaracterized by comprising the step of disposing the core body in theforming metal mold, pouring the thermosetting liquid resin into themetal mold for hot-setting, and forming the roller main body furnishedwith a cylindrical resin layer around the core body, the step ofreleasing the roller main body from the metal mold, followed bychamfering or rounding the corners of the edge parts of the resin layer,and the step of forming the surface layer around the resin layer.

In an embodiment, the step of chamfering or rounding the corners of theedge parts of the resin layer comprises a step of heating the corners tofuse and remove the resin at the corners.

In another embodiment, the step of chamfering or rounding the corners ofthe edge parts of the resin layer comprises a step of coating a solventto the corner for dissolving and removing the resin at the corner.

In another embodiment, the hardness of the resin layer is 25° or lower(JIS-A).

In another embodiment, when the swelling amount of the edge part incomparison with that of the center part of the formed roller body is 1,the swelling amount of the part for chamfering or rounding is 1 to 40times of said swelling amount in the diameter direction as well as theaxial direction.

In another embodiment, the thermosetting liquid resin contains, as maincomponents, (A) polymer containing at least one alkenyl group inmolecule and a repeating unit composing a main chain being mainly oxyalkylene unit or saturated hydrocarbon unit, (B) a hardening agentcontaining at least two hydrosilyl group in molecule, (C) catalyst madehydrosilyl, and (D) conductivity giving agent.

Further, the roller producing apparatus of the invention is to produce aroller composed of the core body and a resin-made elastic layer coveringaround the core body by use of a metal mold having a structure disposedwith the core supporting members holding the roller forming spacetherebetween at both ends of the cylindrical metal mold inserted insidewith the core body, and is characterized in that the core supportingmember is provided with a mold inner pressure adjusting mechanism.

In an embodiment, the mold inner pressure adjusting mechanism providedin the core supporting member is equipped with a volume-variable spareroom communicating with the roller forming space.

In another embodiment, an inner diameter D of the cylindrical metalmold, an outer diameter d of the roller, an outer diameter ds andthickness of the elastic layer are prescribed such that a value of crosssectional shrinkage factor α defined with (D2−d2)/(D2−d_(s)2) is 0.02 to0.06, and the thickness of the elastic layer expressed with (d−ds)/2 is1 mm or more.

In another embodiment, for forming the resin roller, the core supportingmember is provided with a mold inner pressure adjusting mechanism, and amold inner pressure during hot-setting is adjusted to be 100 kg/cm² orlower.

A further method of the invention is to produce a roller for anelectrophotographic apparatus composed of a main body formed with acuring type liquid resin and support shafts for supporting both edges ofthe main body, and is characterized by preparing a roller forming metalmold provided with a space for forming a roller main body as well asprovided with a resin injecting inlet for filling a hardening typeliquid resin in the roller forming space, storing separately a hardeningtype liquid resin containing a cross linking agent and another hardeningtype liquid resin containing a catalyst, respectively measuring to beset amounts thereof, and as mixing both hardening liquid resins,injecting a mixture into the forming space from the resin pouring inletso as to effect a hardening reaction for forming the roller main body.

The roller producing apparatus depending on such a method ischaracterized by providing a roller forming metal mold formed with aspace for forming a roller main body as well as provided with a resininjecting inlet for filling the hardening type liquid resin in theroller forming space, containers for storing separately a hardening typeliquid resin containing a bridging agent and another hardening typeliquid resin containing a catalyst, an injecting device furnished withmeasuring mechanisms for respectively measuring both resins to be setamounts, and a mixing mechanism for mixing both measured liquid resins,injecting, as mixing both resins, a mixture into the forming space fromthe resin pouring inlet so as to effect a hardening reaction for formingthe roller main body.

In an embodiment, a temperature adjusting instrument is provided, and itis preferable to adjust temperature of the hardening type liquid resinat injecting to be within a range of 20 to 70° C., and to adjustviscosity of the hardening type liquid resin at injecting to be 5000poise.

When controlling the electric conductivity of the roller, it isdesirable to add the conductivity giving agent of the same amount to thehardening type liquid resin containing the bridging agent and the otherhardening type liquid resin containing the catalyst.

It is preferable that the composition of the hardening type liquid resinhas polymer containing at least one alkenyl group in molecule and arepeating unit composing a main chain being mainly oxy alkylene unit orsaturated hydrocarbon unit, and the bridging agent has at least twohydrosilyl group in molecule.

An apparatus of injection-forming roller of the invention ischaracterized by having a cylindrical metal mold inserted inside withthe core body and core supporting members detachably fitted to both edgeparts in the axial direction of the cylindrical metal mold as holdingboth edges of the inside inserted core body, and is composed bydisposing heating mechanisms for hot-setting the resin materialintroduced in a roller forming space around the injection forming metalmold having the roller forming space, said core supporting member havinga 1st obliquity tilting at a fixed angle with respect to an axial andvertical direction in the outer wall face, and said heating mechanismhaving an inner wall face contacting to hold the injection forming metalmold under a condition of closing the heating mechanism and having a 2ndobliquity pressing the 1st obliquity to the inner wall face, whereby theinjection forming metal mold is tightened and held.

More specifically, it is preferable that the core supporting member hasa 1st obliquity at the outer periphery, while the heating mechanism haspawl members with the 2nd obliquity pressing the 1st obliquity to theinner wall face under the condition of closing the heating mechanism.

Another specific structure is preferable in that a brim part having the1st obliquity is expanded at an outer periphery of the fitting positionof the core supporting member and the cylindrical metal mold, and thebrim part is engaged with the inner wall face of the heating mechanismunder the condition of closing the heating mechanism, while the groovewith the 2nd obliquity pressing the 1st obliquity is formed in concaveshape.

Preferably, a heat resistant elastic member such as rubber is interposedbetween the 1st obliquity and 2nd obliquity, and desirably the tiltangle of the 1st obliquity is set in a range of 5 to 30°.

Further, a resin roller of the invention is formed with a cylindricalresin-formed body around the core body, and is characterized in that theresin-formed body is formed as standing along the core body toward theedge of the core body.

The resin roller is produced by disposing the core body in the formingmetal mold having a cylindrical metal mold and core supporting membersfurnished at both edge parts of the cylindrical metal mold as well ascausing the core supporting members to hold said both edge parts, andpouring the resin into the metal mold and solidifying it.

In an embodiment, the standing state of the resin-formed body reduces adiameter in arc toward the edge of the core body.

In another embodiment, the standing state of the resin-formed bodyreduces a diameter linearly toward the edge of the core body.

In another embodiment, the standing state of the resin-formed bodyreduces a diameter stepwise toward the edge of the core body.

Incidentally, in the inventive resin roller, it is not necessary thatthe resin-formed body is formed as standing at both edge parts. Ifeither one of the edges is formed to stand, it is sufficient to form oneof the edges positioning forward to stand when extracting a formedproduct from the metal mold. Besides, if both edges are formed to stand,it is not necessary to form both edges in the same shape.

The inventive resin roller forming metal mold holds the cylindricalmetal mold and the core body furnished at both edge parts of thecylindrical metal mold and inserted inside of the cylindrical metalmold, and is characterized in that a ring shaped concave groove isformed at an opening edge of a core holding hole provided in the coresupporting member, said groove being larger in diameter than an outerdiameter of the core body to be inserted in said core holding hole.

In an embodiment of the resin roller forming metal mold, the ring shapedconcave groove reduces the diameter as advancing an inner part of thecore holding hole.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross sectional view showing a forming metal mold of theresin roll in an embodiment of the invention;

FIG. 2 is a cross sectional view showing the forming metal mold of theresin roll in another embodiment of the invention;

FIG. 3 is a cross sectional view showing the forming metal mold of theresin roll in a further embodiment of the invention;

FIG. 4 is cross sectional views showing the relation between the formingmetal mold and attaching positions of the sealing members;

FIG. 5 is a cross sectional view showing the forming metal mold of theresin roll in a still further embodiment of the invention;

FIG. 6 is cross sectional views showing the core bodies and the resinrollers used in the invention;

FIG. 7 is a view showing one example of chamfering swelling corners inedge parts of the resin layer in a yet still embodiment;

FIG. 8 is cross sectional views of the resin layer and the surface layerin this embodiment;

FIG. 9 is a cross sectional view showing an apparatus of producing theroller in another embodiment;

FIG. 10 is an enlarged cross sectional view of an inner pressureadjusting mechanism of this embodiment;

FIG. 11 is a schematic view showing a structure of the apparatus forexplaining the method of producing the roller according to theinvention;

FIG. 12 is schematic views showing the apparatus of injection formingthe roller of another embodiment according to the invention, in which Ais a plan view of this apparatus and B is a bottom view thereof;

FIG. 13 is a schematically cross sectional view showing the side view ofthe apparatus of injection forming the roller of this embodiment;

FIG. 14 is enlarged cross sectional views of elementary parts of theapparatus of injection forming the roller of this embodiment;

FIG. 15 is a schematically cross sectional view showing a modifiedexample of this embodiment;

FIG. 16 is schematic views showing the apparatus of injection formingthe roller of another embodiment according to the invention, in which Ais a plan view of this apparatus and B is a bottom view thereof;

FIG. 17 is a schematically cross sectional view showing the side view ofthe apparatus of injection forming the roller of this embodiment;

FIG. 18 is enlarged cross sectional views of elementary parts of theapparatus of injection forming the roller of this embodiment;

FIG. 19 shows another embodiment, in which A is a vertically crosssectional view of the forming metal mold and B is a cross sectional viewof an elementary part showing a standing state in the resin roller to beformed by the metal mold;

FIG. 20 shows another embodiment, in which A is a vertically crosssectional view of the forming metal mold and B is a cross sectional viewof an elementary part showing a standing state in the resin roller to beformed by the metal mold;

FIG. 21 is a further embodiment, in which A is a vertically crosssectional view of the forming metal mold and B is a cross sectional viewof an elementary part showing a standing state in the resin roller to beformed by the metal mold;

FIGS. 22A to 22C are cross sectional views of the resin rollers showingexamples of the core bodies to be employed to the invention;

FIGS. 23A to 23G are cross sectional views showing examples of thestanding states at edge faces of the formed bodies in the resin rollersof the invention;

FIG. 24 is a perspective view of an ordinary resin roller;

FIG. 25 is a cross sectional view showing a state of resin injecting inthe core body and the forming metal mold in the prior art;

FIG. 26 is a cross sectional views showing states of resin injecting inthe core body and the forming metal mold in the prior art;

FIG. 27 is a cross sectional view of elementary parts of theelectrophotographic apparatus;

FIG. 28 is a perspective view of a conventional resin roller;

FIG. 29 is a cross sectional view of a conventional resin roller;

FIG. 30 is a cross sectional view of a conventional resin roller;

FIG. 31 is a cross sectional view showing a resin pouring state into aforming metal mold;

FIG. 32 is a cross sectional view of one example of a roller main bodyformed by the forming metal mold;

FIG. 33 is a cross sectional view of another example of a roller mainbody formed by the forming metal mold;

FIG. 34 is a cross sectional view of edge corners of a resin layer andthe surface layer of the prior art;

FIG. 35 is a cross sectional view showing the prior art roller producingapparatus;

FIG. 36 is a schematic view showing the apparatus structure forexplaining the prior art roller producing apparatus;

FIG. 37 is a schematically cross sectional view showing another exampleof the conventional injection forming apparatus; and

FIG. 38 is cross sectional views showing separating states of the resinbody and the core when releasing the formed body from the mold in theresin roller formed body and the forming metal mold in the prior art.

MOST PREFERRED EMBODIMENT OF THE INVENTION Embodiment 1

The resin roller of the invention will be explained with reference tothe attached drawings.

As shown in FIG. 1, the forming metal mold 1 has the cylindrical metalmold 13 and a pair of core supporting members 14, 14 disposed at bothends of the cylindrical metal mold 13, and the cylindrical metal mold 13and the pair of core supporting members 14 define the roller formingspace 15. One of the core supporting members 14 is provided with theresin injecting inlet 16.

The core body 21 has the same outer diameter over a lengthwisedirection, and is located at ends 21 a in concave parts 17 formed in thecore supporting members 14. After forming, a cylindrical formed body 12is produced which is composed of resin at the center part of the corebody 21.

Shapes of the core body 21 are pertinent to those shown in FIGS. 6A to6C, and for the core body 21 of the resin roller, known optionalmaterials, for example, metal materials or conductive resin materialsare applicable as the core body 21 of the invention.

By the way, the core body 21 shown in FIG. 6A is a bar like materialhaving the same outer diameter, the core body 21 shown in FIG. 6B isformed at both ends with engaging parts 31 for attaching to a machine,and the core body 21 shown in FIG. 6C is formed at one end with anengaging part 31 of plural steps.

As to optional dimensions of known resin rollers, the forming metalmold, the core body 21 and the sealing members are applicable, andgenerally, a diameter is 10 to 30 mm and a length is 200 to 400 mm.

The cylindrical metal mold 13 and the core supporting member 14 arecomposed of known arbitrary materials for thermosetting liquid resin,preferably pre-hardened steel, quenched steel, non-magnetic steel,carbon tool steel, or corrosion resistant steel (stainless steel).

The core supporting members 14 have steps 20 for holding cylindricalmetal mold 13 at the periphery thereof and the concave parts 17 at thecenter parts thereof, and the pair of core supporting members 14, 14 arelocated in opposition to both ends of the cylindrical metal mold 13,while the cylindrical metal mold 13 is fitted at both ends to steps 20of the core supporting members 14. Thus, the forming metal mold 1 iscomposed. The core body 21 is inserted at its ends in the concave parts17 formed in the core supporting members 14, and is disposed in theforming metal mold 1.

As shown in FIG. 1, the core body 21 is provided with grooves 23 forholding E-rings 22, and the sealing members 24 are furnished to contactthe E-rings 22 held in the grooves 23 and contact edge faces 14 a of theroller forming space 15 of the core supporting members 14.

As to positions for providing the E-rings 22 and the sealing members 24,as illustrated in FIG. 4, if a distance L2 between ends of the sealingmember s 24 at both edges is made larger than a distance L1 between endsof the pair of core supporting members 14, 14 under a condition ofsetting up the forming metal mold 1, so that the sealing members 24 arecompression-deformed owing to pressure when incorporating the coresupporting members 14 to the cylindrical metal mold 13, this manner ismore preferable for increasing the sealing effect.

As to the quality of the sealing member, available are resin materialsas polyethylene, polypropylene, polyamide, polycarbonate or polyimide,such resin materials of said resin materials rendered to be conductiveas needed, or metal materials as aluminum, brass, iron, and of coursesuch materials should be selected which are not fused and deformed whenhot-setting after pouring.

Especially, as materials effective against compressive deformation bythe setting force of the core supporting member 14 and the resinleakage, available are elastic resin materials as polyvinylchloride,silicone, polyurethane, EPDM or NBR, such resin materials of said resinmaterials rendered to be conductive as needed, or metal materials ascopper, brass or phosphor bronze.

The sealing member 24 is manufactured by injecting formation orextruding formation, punching process of a sheet or plate, forging orcasting, and shapes have preferably inner diameters closing to the corebody 21, thickness of 0.1 to 3 mm and length of 0.1 to 20 mm, morepreferably thickness being 0.1 to 2 mm and length being 1 to 5 mm. Crosssectional shapes are circular, semi-circular, oval or square.

The above materials are made sheets, and if necessary, a tape coatedwith an adhesive on the rear side is wound on the sheet to make asealing member 24. Otherwise, if a thermal shrinkage tube produced witha thermally shrinking resin material is applied to the core body 21, andheated and shrunk, it can be attached to a desired position.

Using mass-produced O-rings, the sealing members 24 are cheaply got andfurther cost-down is possible. For example, using O-rings on the market,if the outer diameter of the core body 21 is 5 to 10 mm, a diameter incross section of the O-ring is ordinarily 1.9 mm, and if the distance L2between the ends of the pair of sealing members 24 is determined suchthat the O-ring is compressed by 0.5 mm by the setting force of the coresupporting member 14, a result is more preferable.

EMBODIMENT 2

FIG. 2 shows another embodiment.

The core body 21 is attached with cylindrical members 25, and thesealing members 24 are furnished on the core body 21 so as to contactthe cylindrical member 25 and contact edge faces 14 a at the side of theroller forming space of the core supporting member 14. The cylindricalmember 25 is attached to the core body 21 by manners as adhesion,caulking, urging insertion by force-fitting dimension, or insertingformation into the core body 21. In either way, such manners are adoptedwhich are not easily moved by vibration or expansion pressure whenforming a formed body 12.

As to the quality of the cylindrical member 25, available are resinmaterials as polyethylene, polyproplylene, polyamide, polycarbonate orpolyimide, such resin materials of said resin materials rendered to beconductive as needed, or metal materials as aluminum, brass, iron,copper or phosphor bronze, and of course such materials should beselected which are not fused and deformed when hot-setting afterpouring.

In particular, for urging to insert the cylindrical member to the corebody 21, making use of elasticity of the resin, useful are elastic resinmaterials as polyvinylchloride, silicone, polyurethane, EPDM or NBR,such resin materials of said resin materials rendered to be givenconductive as needed.

The above materials are made sheets, and if necessary, a tape coatedwith an adhesive on the rear side is wound on the sheet to make asealing member 24. Otherwise, if a thermal shrinkage tube produced witha thermally shrinking resin material is applied to the core body 21, andheated and shrunk, it can be attached to a desired position.

The dimensions of the cylindrical member are preferably thickness of 0.5to 3 mm and length of 2 to 20 mm, more preferably thickness being 0.5 to2 mm and length being 2 to 10 mm.

Also as to the attaching position of the cylindrical member 25 and thesealing member 24, as above mentioned, if the distance L2 between endsof the sealing members 24 at both edges is made larger than the distanceL1 between ends of the pair of core supporting members 14 under thecondition of setting up the forming metal mold, so that the sealingmember s 24 are compression-deformed owing to pressure whenincorporating the core supporting members 14 to the cylindrical metalmold 13, this manner is more preferable for increasing the sealingeffect.

The quality, dimensions and shapes are the same as those of the abovementioned embodiment.

EMBODIMENT 3

FIG. 3 shows another embodiment.

Cylindrical sealing members 26 are attached so as to contact to the edgefaces 14 a at the side of roller forming space of the core supportingmembers 14 with respect to the core body 21 by manners as adhesion,caulking, or urging insertion by force-fitting dimension, or insertingformation into the core body 21. Especially, in a case of elastic resinmaterials as synthetic rubbers to be elastically deformed by tension, itis effective to select those of smaller inner diameter than that of thecore body 21. In either way, such manners are of course adopted whichare not easily moved by vibration or expansion pressure when forming aformed body 12.

As to the attaching position of the cylindrical sealing member 26, ifthe distance L2 between ends of the cylindrical sealing members 26 atboth edges is made larger than the distance L1 between ends of the pairof core supporting members 14 under the condition of setting up theforming metal mold, so that the sealing members 24 arecompression-deformed owing to pressure when incorporating the coresupporting members 14 to the cylindrical metal mold 13, this manner ismore preferable for increasing the sealing effect.

As to the quality of the cylindrical sealing member 26, available areresin materials as polyethylene, polypropylene, polyamide, polycarbonateor polyimide, such resin materials of said resin materials rendered tobe conductive as needed, or metal materials as aluminum, brass or iron,and of course such materials should be selected which are not fused anddeformed when hot-setting after pouring.

Especially, if expecting such materials effective against compressivedeformation by the setting force of the core supporting member 14 andthe resin leakage, available are elastic resin materials aspolyvinylchloride, silicone, polyurethane, EPDM or NBR, such resinmaterials of said resin materials rendered to be conductive as needed,or metal materials as copper, brass or phosphor bronze.

The sealing member 26 is manufactured by injecting formation orextruding formation, punching process of a sheet or plate, forging orcasting, and shapes have preferably inner diameters closing to the corebody 21, thickness of 0.01 to 3 mm and length of 0.5 to 20 mm, morepreferably thickness being 0.01 to 2 mm and length being 1 to 5 mm.Cross sectional shapes are circular, semi-circular, oval or square.

The above materials are made sheets, and if necessary, a tape coatedwith an adhesive on the rear side is wound on the sheet to make asealing member 26. Otherwise, if a thermal shrinkage tube produced witha thermally shrinking resin material is applied to the core body 21, andheated and shrunk, it can be attached to a desired position.

EMBODIMENT 4

FIG. 5 shows another embodiment.

The core body 21 is defined with grooves 27 for attaching the sealingmembers 24, and the sealing members 24 are attached so as to contact theedge faces 14 a of the core supporting members 14. As to the attachingposition of the sealing member 24, if the distance L2 between ends ofthe sealing member s 24 at both edges is made larger than the distanceL1 between ends of the pair of core supporting members 14 under thecondition of setting up the forming metal mold, so that the sealingmembers 24 are compression-deformed owing to pressure when incorporatingthe core supporting members 14 to the cylindrical metal mold 13, thismanner is more preferable for increasing the sealing effect.

The dimensions of the sealing member 24 are determined such that a partof the sealing member 24 projects outside of the outer periphery of thecore body 21 from the groove when the sealing member 24 is attached intothe groove 27.

As to the quality of the sealing member 24, available are resinmaterials as polyethylene, polyproplylene, polyamide, polycarbonate orpolyimide, such resin materials of said resin materials rendered to beconductive as needed, or metal materials as aluminum, brass or iron, andof course such materials should be selected which are not fused anddeformed when hot-setting after pouring. Especially, as such materialseffective against compressive deformation by the setting force of thecore supporting member 14 and the resin leakage, available are elasticresin materials as polyvinylchloride, silicone, polyurethane, EPDM orNBR, such resin materials of said resin materials rendered to beconductive as needed, or metal materials as copper, brass or phosphorbronze. If mass produced O-rings are used, the sealing members arecheaply available to cost down.

The sealing member 24 is manufactured by injecting formation orextruding formation, punching process of a sheet or plate, forging orcasting, and shapes have inner diameters closing to the groove 27 of thesealing member, and the outer diameter has preferably a dimensionlargely protruding 10 to 90% of the thickness of the sealing member fromthe outer peripheral face. The thickness is preferably 0.1 to 5 mm, thelength is 0.1 to 20 mm and the thickness is 1 to 3 mm, more preferablythe thickness is 1 to 3 mm and the length is 1 to 20 mm. Cross sectionalshapes are circular, semi-circular, oval or square.

The depth of the groove 27 for holding the sealing member 24 to the corebody 21 is preferably 10 to 90% of the thickness of the sealing member24.

Next, explanation will be made to the method of producing the resinroller of the invention by use of the core body 21 and the structure ofthe outer periphery of the same.

Polysiloxane based hardening agent and the conductivity giving agent(carbon black) are mixed in terminal allylated polyoxypropylene basedpolymer, and when forming a roller of an outer diameter being φ 16 mmand a length of a resin-formed body being 250 mm in a liquid resininjecting and pouring machine, it is preferable that a viscosity of themixed and poured resin is 200 to 5000 poises and a pouring pressure is0.5 to 15 MPa, though depending on the number of mixing part of theconductivity giving agent.

When the thickness of the resin formed body 12 is 4 mm in the roller ofthe above mentioned dimensions, the diameter of the resin injectinginlet of the metal mold is preferably 1 to 2 mm. Further, as to thedirection of the metal mold when pouring, preferably the lengthwisedirection of the metal mold stands vertically for pouring from the lowerpart of the metal mold.

The metal mold may be heated depending on any arbitrary methods.Specifically, for example, there is a method of heating in a heatingoven having heating fans, a method of heating by arranging electricheaters around the metal mold, or a method of heating by arranginginduction heating coils around the metal mold.

For the temperature of the metal mold, it is possible to select anytemperatures enabling to pour and hot-set the thermosetting liquidresin, and at pouring the resin, desirable are temperatures for easilypouring the resin and not hardening, for example, 20 to 70° C. Theheating temperature of the resin is preferably 80 to 200° C., thoughdepending on the amount of a harden-retarding agent to be mixed in theresin.

As roller forming resin materials available to the inventive formingmethod, resins of heat-removal hardening are employed, for example,silicone, polyurethane, acrylonitrile.butadiene copolymer (NBR),ethylene.propylene.diene. methylen copolymer (EPDM).

The thermosetting liquid resin may be added with other kinds ofadditives as needed. For example, if a resistance controlling agent ascarbon is added, electric resistance of the roller can be controlled.

As the above mentioned thermosetting liquid resin materials, laterexplained hardening compositions may be used. The roller forming resincomposed of reaction hardening substance of the hardening compositionhas an especially soft structure, and even if the thickness is madethin, it displays enough an elastic effect. Containing oxyalkylene unitin molecule, it has low viscosity before hardening and is easily dealt,and containing saturated hydrocarbon unit, it is low in water absorptionrate, and preferably cubic variation and variation of roller resistanceare low.

That is, it is preferable that the thermosetting liquid resin materialcontains, as main components,

-   (A) polymer containing at least one alkenyl group in molecule and a    repeating unit composing a main chain being mainly oxy alkylene unit    or saturated hydrocarbon unit,-   (B) a hardening agent containing at least two hydrosilyl group in    molecule,-   (C) catalyst made hydrosilyl, and-   (D) conductivity giving agent.

The thermosetting liquid resin is added, if necessary, with materialsfor adjusting thermosetting reaction such as hardening agent, hardeningaccelerator, hardening retardant or others. Or, organic or inorganicfillers may be added. Further, some kinds of organic or inorganicpigments, thickener or mold releasing agent may be added.

Indefinite examples of the invention will be explained.

Example A-1

The resin roller of the roller outer diameter being φ 16 mm and thelength of a resin formed body 12 being 250 mm was formed by use of themetal mold 1 shown in FIG. 3.

The outer diameter of the core body 21 was 6 mm, and a silicone tube ofthe inner diameter serving as the sealing member 26 being 4 mm, theouter diameter being 6 mm and the length being 5 mm was urged into andattached to the core body 21, and the attaching position was designedsuch that the sealing member 26 was compressed by 0.5 mm in the axialdirection owing to the setting force of the core supporting member 14.

The inner diameter of the concave part 17 of the core supporting member14 and the space of the end part 21 a of the core body 21 were 15μ.

The used thermosetting liquid resin was 600 poises in the viscosity inthe mixed resin shown in the under table.

In the liquid resin injecting and pouring machine, the mixed resinmaterial was poured into the metal mold having the resin injecting inlet16 of 1.5 mm from the lower portion under the pouring pressure of 4 MPa,the metal mold standing vertically in the lengthwise direction.

The metal mold was arranged within the heating oven provided with theheating fans and was heated by setting the atmospheric temperaturewithin the heating oven to be 140° C. for 20 minutes and releasing fromthe metal mold, and a formed product was obtained.

As a result, at the ends of the obtained roller, no resin leakageoccurred.

TABLE 1 Components of hardening compositions Wt parts (A) Terminalallylated polyoxypropylene based polymer 100 (Number average molecularweight (Mn) 8000) (B) Polysiloxane based hardening agent 6.6 (SiH valueper 100 g: 0.36 mol) (C) 10% isopropyl alcohol solution of 0.06chloroplatinic acid (D) Carbon black 7 (made by Mitsubishi Co., Ltd.Product name “3030”)

According to the invention, even if using the core body having the samesizes in the center part of the core body (a part of the resin-formedbody) and the outer diameter of the end part thereof, no resin leakageoccurred at the rod portion of the resin roller, and good products maybe obtained cheaply and stably.

EMBODIMENT 5

The resin roller 10 a may be produced by use of the same metal mold 120as having explained with the prior example show in FIG. 31.

In the metal mold 120, the core body 21 is in advance placed and thethermosetting liquid resin is poured into the roller forming space 15through the resin injecting inlet 16 from the resin injecting nozzle 18.

After completion of filling the resin in the metal mold 120, the wholeof the metal mold 120 is heated to hot-set the resin charged in theroller forming space 15. Hot-setting the resin, the core supportingmembers 14, 14 are removed upward and downward respectively along anaxial direction from the cylindrical metal mold 13. Subsequently, thecore body 21 is extruded from the cylindrical metal mold 13 to take outa formed product 10 b (roller main body) held within the cylindricalmetal mold 13. The roller main body 10 b is formed by providing thecylindrical resin layer 12 a around the core body 21.

As the roller forming resin material usable to the inventive formingmethod, a known thermosetting liquid resin is used. For example,polyurethane, ethylene.propylene.diene.methylene copolymer (EPDM) orsilicone may be used, and it is more preferable to use the thermosettingliquid resin material mixed with polysiloxane based hardening agent.

The thermosetting liquid resin may be added with various kinds ofadditives as needed. For example, if adding the resistance controllingagent as carbon, the electric resistance of the roller can becontrolled.

The thermosetting liquid resin is added, if necessary, with materialsfor adjusting thermosetting reaction such as hardening agent, hardeningaccelerator, hardening retardant or others. Or, organic or inorganicfillers may be added. Further, some kinds of organic or inorganicpigments, thickener or mold releasing agent.

The roller main body 10 b produced by the above mentioned forming methodhas the resin layer 12 a swelling parts as seen in FIG. 32 whenreleasing from the mold. A mechanism of the swelling phenomenon at theedge is explained that the swelling is generated by thermal expansionand shrinkage owing to temperature difference between temperatures atpouring the resin into the metal mold and after releasing from the mold,the amount of shrinkage in the axial direction of the resin layer 12 ais larger than that in the peripheral direction, and the resin layer 12a is adhered to the core body 21.

The cylindrical metal mold 13 and the core supporting members 14, 14have tolerances of respective parts and assembling spaces, and so-calledparting lines occur. If the spaces become large owing to such asabrasion in the respective parts when setting up the metal mold, theresin flows into the spaces and burrs 75 are created as shown in FIG.33.

Corners 74 swelling in the roller main body by dimensional shrinkage orburrs are processed to round by the chamfering.

As to the process of the edges or corners, the machining or polishingprocesses by known cutting edges or grinding stones, and it is morepreferable that previously heated metal-made heating members 130 are, asshown in FIG. 7, contacted or approached to the corners 74 at the edgesof the roller main body 10 b, and either of the heating member 130 orthe roller main body 10 a is rotated to thermally decompose and removeparts of the resin layer 12 a, otherwise a hot blast or a laser heatingthermally decompose and remove parts of the resin layer 12 a.

The surface temperature of the heating member 130 is set to be higherthan thermally decomposing temperatures of selected resins, and in casethe resin layer 12 a is formed with the thermosetting liquid resin mixedwith polysiloxane based hardening agent in poly urethane or terminalallylated polyoxypropylene based polymer, it is preferable that thesurface temperature of the heating member 130 is set to be 200° C. orhigher, in case the resin layer 12 a is formed with EPDM, 250° C. orhigher is preferable, and in case of silicone, 350° C. or higher ispreferable. For shortening the treating time, the above mentionedrespective temperatures should be desirably heightened around 50° C.higher than said temperatures.

As to the process of the corner 74 at the edge of the resin layer 12 a,such a method may be also adopted which coats a solvent to parts to beprocessed at the edge of the resin layer 12 a for dissolve to removeparts of the resin layer 12 a.

Practically, preferable is a method that a solvent enabling to dissolvethe selected resin material is caused to soak into the resin layer 12 aof the roller main body 10 b, and either of the cloth, felt or theroller main body 10 b is rotated to contact the corner 74 at the edge ofthe resin layer 12 a and dissolve to remove the resin.

As to selection of solvents, in case the resin layer 12 a is formed withthe thermosetting liquid resin mixed with polysiloxane based hardeningagent in poly urethane or terminal allylated polyoxypropylene basedpolymer, available are keton based solvent (for example, acetone, MEK)or hydrocarbon solvent (for example, toluene, xylene) or ether basedsolvent (for example, diethyl ether), if the resin layer 12 a is formedwith EPDM, hydrocarbon solvent (for example, toluene, xylene) is usable,and if the resin layer 12 a is formed with silicone, acid or alkaline(for example, hydrochloric acid, caustic soda) may be used. Using thesesolvents, the corner 74 at the edge of the resin layer 12 a can bedissolved to remove.

Shapes of processed corner 74 at the edge of the resin layer 12 a aredesirably chamfered or circular-arc processed (rounding process). It ispreferable that the processed dimensions in both of the axial anddiameter directions are larger 1 to 40 times of a swelling amount of theedge part having a larger diameter than the center part of the formedroller main body 10 b. Herein, the swelling amount of the edge part ismeant by a dimension until the opposite face of the swelling part of theedge parts on the basis of the extending face of the center position ofthe resin layer 12 a of the roller main body. For example, if theswelling amount is 100μ, it is sufficient that the edge part of theresin layer 12 a is 100 μm to 4 mm chamfered or circular-arc processedfrom the edge face of the resin layer 12 a in the axial direction and is100 μm to 4 mm chamfered or circular-arc processed from the referenceface in the diameter direction.

If the processed dimension of the corner 74 at the edge part of theresin layer 12 a is smaller than the above mentioned ranges, an effectof contributing to a long life of the surface layer 12 b is small, andif exceeding said ranges, the length in the axial direction necessary todeveloping of the resin roller is short, and consequently, the length ofthe resin roller 10 a in the axial direction should be large, and inturn an apparatus is large scaled.

In a case of the resin layer 12 a having the low rubber hardness, ifcontacting to the cutting edge or the grinding stone in the machining orpolishing processes, the surface of the resin layer 12 a becomes concaveor chatter appears in the surface, and the surface is difficult to bemachined or polished.

Thus, in case such a method is selected that the corner 74 is heated bychamfering or rounding to thermally dissolve the resin from the corner74, or the solvent is coated to the corner 74 to dissolve the resintherefrom, if using the thermosetting liquid resin of the formed rubberhardness being 25° or lower (JIS-A), the process is effective anddesirable.

After releasing the roller main body 10 b having the core body 21 andthe resin layer 12 a from the metal mold 120, and chamfering or roundingthe corner 74 swelling larger in the diameter than the center part ofthe resin layer 12 a of the roller main body 10 b by shrinking of thedimension or occurrence of burrs, the surface layer 12 b is coated andhardened around the resin layer 12 a of the roller main body 10 b.

No especial limitation is made to materials forming the surface layer 12b, but from viewpoint of causing the developing agent to wellminus-charge, nylon based (polyamide group) or polyurethane basedmaterials are preferable, and fluoro rubber is desirable from viewpointof causing the developing agent to well plus-charge.

No especial limitation is also made to coating methods of the surfacelayer 12 b, and ordinary are a method of covering a tube on the surfacelayer 12 b by the thermal shrinkage, or a method of applying thesolution enabling to form the surface layer 12 b by means of dipping,spraying or coater in response to viscosity and drying it.

Indefinite examples of the invention will be explained.

Example B-1

As the thermosetting liquid resin material, a resin raw material wasused where polysiloxane based hardening agent and the conductivitygiving agent (carbon black) were mixed in terminal allylatedpolyoxypropylene based polymer shown in Table 1.

This resin raw material was used to form a roller min body 10 b of anouter diameter being φ 16 mm and a length of a resin layer 12 a being250 mm in the liquid resin injecting and pouring machine by use of themetal mold 120 shown in FIG. 31.

A viscosity of the mixed and poured resin was 600 poises, and a pouringpressure was 2 MPa. The diameter of the resin injecting inlet providedin the core supporting member 14 of the metal mold 120 was 1.5 mm, andthe metal mold 120 was directed, standing vertically in the lengthwisedirection, and the mixed resin material was poured into the metal moldfrom the lower portion.

The metal mold 120 was arranged within the heating oven provided withthe heating fans and was heated by setting the atmospheric temperaturewithin the heating oven to be 140° C. for 20 minutes, and releasing fromthe metal mold 120, a formed product (roller main body) was obtained.

As a result, it was observed that the corner 74 at the edge part of theresin layer 12 a of the roller main body 10 b swelled 100μ in comparisonwith the outer diameter of the center part of the resin layer 12 a.

The roller main body was attached at both end shafts to a rotarymachining disc, and soldering irons (30 w) heated at around 300° C. werecontacted to the corners 74 for 5 minutes, and the roller main body wasrotated to fuse and remove the resin of the corner.

As a result, the roller main body was obtained, which was smoothlyrounded 1 mm from the edge part in the axial direction and 1 mm from thesurface in the diameter direction.

The solid content of the mixture shown in Table 2 was diluted to 5% witha mixed solvent of DMK (N,N-dimethyl formamide): MEK (methyl ethylketone)=1:1 (weight ratio), and was still left for one hour to make asolution, and the resin for forming the surface layer was carried outdipping around the resin layer of the roller main body and dried to formthe surface layer.

The thus obtained resin roller was installed to contact φ 30 mmsensitive drum at a 2 mm width, and when the resin roller wascontinuously rotated at rotation number of 240 rpm to perform anendurance test, the surface layer did not peel until 16 hours.

Comparative Example B-1

The roller main body formed in Example B-1 was not chamfered nor roundedat the corners, the surface layer of which was coated and driedsimilarly to the above procedure, and the resin roller was obtained.

The obtained resin roller was subjected to the endurance test under thesame conditions as above, and after 3.5 hours the surface layer of thecorner started to peel, and after 4 hours of the test, the peeling ofthe surface layer spread toward the center part from the edge parts.

TABLE 2 Components of the composition of the surface layer Wt. partsPolycarbonate urethane 100 Acrylic fine particles 30

According to the invention, the resin layer is formed by pouring thethermosetting liquid resin into the forming metal mold and hot-settingit, and the resin layer is chamfered or rounded at the corners of theedge parts, followed by forming the surface layer on the surface of theresin layer, and therefore, the film of the surface layer can be made adesired thickness over the full face of the roller, and the surfacelayer is restrained from exfoliation or abrasion from the resin layer,so that the durability of the resin roller is increased, andconsequently, the inventive resin roller can be served for a long periodof time without exchanging many kinds of rollers employed inelectrophotographic system such as laser printers, copiers, facsimiledevices using the resin rollers.

EMBODIMENT 6

The roller producing apparatus is, as shown in FIG. 9, mainly composedof the cylindrical metal mold 1 and the upper and lower core supportingmembers 2 a, 2 b, and the upper core supporting member 2 a is equippedwith a mold inner pressure adjusting mechanism 220 for adjusting theinner pressure of the metal mold.

The cylindrical metal mold 1 is inserted with the core body 21, and thecore body 21 is inserted at both ends in axis receiving holes 3 formedin the core supporting member 2 a, 2 b fitted in both upper and loweropening parts of the cylindrical metal mold 1, whereby the core body 21is supported at the center position of the cylindrical metal mold 1.

The cylindrical metal mold 1 is shaped in seamless pipe, and the insideface is preferably performed with fluorine resin coating or electrolessplating from the viewpoint of releasing from the mold.

On the other hand, the upper and lower core supporting members 2 a, 2 bare defined with convex parts 4 for fitting inward the cylindrical metalmold 1 to form a concave-convex fitting with the cylindrical metal mold1, a so-called faucet structure. The outer peripheral faces 5 of thecore supporting members 2 a, 2 b for fitting the inner peripheral faceof the cylindrical metal mold 1 may be tapered. By being tapered, thecore supporting members 2 a, 2 b are easily detachably attached to thecylindrical metal mold 1, and the axis receiving holes 3 can be securelypositioned at the center position in the axial direction of thecylindrical metal mold 1.

Preferably, the cylindrical metal mold 1 and the outer diameters of thecore supporting members 2 a, 2 b have the same size. The core supportingmembers 2 a, 2 b and the cylindrical metal mold 1 may be tightened byscrewing or clamping, though not shown.

The lower core supporting member 2 b is provided with a pouring hole 6for pouring the liquid resin, and for this hole, a closure mechanism 7is provided to check counterflow of an expanded resin in the metal moldat hot-setting. The exemplified closure mechanism 7 is crossed in thepouring hole 6 with a pin B having a reduced diameter part on the way inthe lengthwise direction, and by moving the pin 8 back and forth, areleasing condition of positioning the reduced diameter part in thepouring hole 6 is switched with another closing condition. In addition,the pouring hole 6 communicates with a nozzle touch part 9 formed byrecessing in semi-sphere in the lower face of the core supporting member2 b, and if pressing the pouring hole 6 to a nozzle (not shown) having afront end of the semi-sphere corresponding to the nozzle touch part 9,an excellent sealing performance is displayed and the liquid resin canbe supplied without leakage.

FIG. 10 shows in detail the mold inner pressure adjusting mechanism 220provided in the upper core supporting member 2 a for adjusting innerpressure of the roller forming space 10.

The mold inner pressure adjusting mechanism 220 as shown in FIG. 10 hasa spare room 221 of variable volume whose inner space communicates withthe roller forming space 100 via a narrow hole 222.

The volume in the spare room 221 is varied to adjust the inner pressurein the roller forming space 100, and the adjustment is carried out,aiming at maintenance of constant values of the inner pressure aspassing a time of hot-setting, so as not to exceed the inner pressurewhen hot-setting the thermosetting liquid resin. Structures enablingsuch adjustment are variously assumed, and a representative one may beexemplified as shown in that the spare room 221 is provided inside witha plunger vertically moving under an air tight condition, and theplunger 224 is pressed downward by a spring 223. Preferably, the moldinner pressure adjusting mechanism 220 is provided at the upper side ofthe metal mold in relation with attachment.

The mold inner pressure can be adjusted by selecting spring constant ofthe mold inner pressure adjusting mechanism 220. Practically, when themold inner pressure is 0 kg/cm², the volume in the spare room is 0, andas the mold inner pressure rises, the spring mechanism is compressed,and the volume in the spare room increases by the amount of compression.A state of the mold inner pressure being 0 kg/cm² means such a statethat the liquid resin is not fully charged in the roller forming space100, and under this state, the liquid resin does not go into the spareroom 221, and an edge face 224 of the plunger is placed at the undermostpart as shown with an two-dotted imaginary line, and the volume of thespare room 221 is 0. By the way, there is furnished an instrument fordischarging an air compressed in company with the resin pouring into theroller forming space 100, though not shown.

When completing the charge of the liquid resin into the roller formingspace 100 and accomplishing fullness of the liquid resin into the rollerforming space 100, an operation starts to hot-set the liquid resin, andwhen hot-setting, the liquid resin is expanded and flows into the spareroom 221 through the narrow hole 222. Preferably, the volume in thespare room when the spring is fully compressed is set to be 5% or moreof the roller forming space 100. It is desirable to set the springconstant such that the mold inner pressure is 100 kg/cm² or lower whenthe spring mechanism is fully compressed, and more desirable is to set60 kg/cm² or lower. If the mold inner pressure exceeds 100 kg/cm² whenhot-setting, the resin leaks into the parting line between thecylindrical metal mold 1 and the core supporting members 2 a, 2 b togenerate burrs. The diameter of the narrow hole 222 communicating theroller forming space 100 with the spare room 221 is desirably set to beφ 1 mm to φ 3 mm for cleaning easiness. The outer diameter d of theroller is practically expressed with the following formula, thoughdepending on the amount of the resin flowing into the spare room 221.d=(4×(V−V1)/(π×L))½herein;

-   V: Volume of the forming space-   V1: Amount of the resin flowing into the spare room-   L: Length of the part of the roller elastic layer.

An inventor has found that if the outer diameter of the roller isexpressed by introducing an parameter of an cross sectional shrinkagepercentage α, the inner pressure at hot-setting can be evaluated inrelation with the cross sectional shrinkage percentage α, and values ofthe cross sectional shrinkage percentage α when easily releasing fromthe mold and creating no burr, fall within an almost fixed range even ifthe roller sizes or thickness of the elastic layer are different, and ifthe inner pressure when hot-setting is fixed, this α is also fixedaccordingly. The cross sectional shrinkage percentage α is expressedwith the under formula.α=(D2−d2)/(D2−d _(s)2)herein, the symbols mean as follows.

-   D: Inner diameter-   d: Outer diameter of the roller-   ds: Outer diameter of the core body (Core diameter).

As a result of study, it was found that the cross sectional shrinkagepercentage a of easily releasing from the mold by a bit cooling andcreating no burr is 0.02 to 0.06. The outer diameter d of the roller isa value when measuring at a room temperature.

If the cross sectional shrinkage percentage a is smaller than 0.02, thereleasing from the mold is easily inferior and burrs are outstanding onthe circumference of the elastic layer. On the other hand, if the crosssectional shrinkage percentage a is larger than 0.06, voids easily occurinside and on the surface of the elastic layer, and variations of theouter diameter are easy to grow in the axial direction.

Further, it has been found that the mold inner pressure at hot-settingfor a to fall in the range of 0.02 to 0.06 is 100 kg/cm² or lower.

As the value of the preferable cross sectional shrinkage percentage a isapparent, it is possible to design the metal mold for obtaining rollersof easily releasing from the mold without creating burrs. For example,when the inner diameter D of the cylindrical metal mold is φ16 mm andthe core diameter is φ10 mm, the outer diameter d of the cross sectionalshrinkage percentage a being 0.02 is φ15.90 mm. Further, the outerdiameter d of the cross sectional shrinkage percentage α being 0.06 isφ15.70 mm. In short, the roller outer diameter for good forming rangesφ15.70 mm to φ15.90 mm.

The invention has been explained, referring to one embodiment, and ofcourse, the invention may be applied to another apparatus of a structurewhich holds the roller forming space between both ends of thecylindrical metal mold inserted inside with the core body for disposingthe core supporting members.

Explanation will be made to experiments carried out for confirmingeffects of the invention.

Example C-1

The roller producing apparatus shown in FIG. 9 was used. The cylindricalmetal mold was treated on the inside with the electroless plating andthe inner diameter was φ 16.00 mm. The outer diameter of the core bodywas φ 10 mm, a maximum volume of the spare room was 1.6 ml, and thespring mechanism was absent (corresponding to the spring constant 0).The thermosetting liquid resin (silicone group) was poured at 20° C.from the lower pouring hole, and after filling the resin in the formingspace, the closure mechanism was closed. At that time, the mold innerpressure adjusting mechanism was checked with a stopper not to movetogether with increasing of the mold inner pressure at pouring. Whencompleting the pouring, the mold inner pressure was 0. Subsequently, theresin was hot-set 140° C.×20 min in a hot blast oven, cooled andreleased from the mold. Thus, the elastic rollers were produced. Therollers were evaluated. Testing number were 10 pieces, average outerdiameters of the rollers were φ 15.77 mm and variations of the outerdiameter was 15 μm. Results were as follows. The evaluations of theresin leakage were performed by evaluating the burr occurrence in theparting line being the fitting part between the cylindrical metal moldand the upper and lower core supporting members and by evaluating theresin leakage from the closure mechanism part provided on the way of thepouring hole 6 (called as “lower closure mechanism part”). A method ofreleasing from the mold was to secure the cylindrical metal mold under acondition of taking off the upper and lower core supporting members, andpush the shaft of the formed body at the front end thereof by the rod,and the pushing load at that time was measured by a load cell. Resultswere as follows.

-   -   Mold releasing load: 15 kg (No scratch at releasing)    -   Burr condition: No at the parting line part    -   Resin leakage: No at the lower closure mechanism part    -   Roller average outer diameter: φ 15.77 mm    -   Variation of the outer diameter: 15 μm

Example C-2

The spring mechanism was set such that the maximum value of the moldinner pressure was 60 kg/cm². The shape of the spare room was φ 10mm×maximum length of 20 mm, and the spring mechanism had the springconstant of (π/4)×12×60=47 kg/20 mm. Other conditions were the same asthose of Example C-1. Results were as follows.

-   -   Mold releasing load: 15 kg (No scratch at releasing)    -   Burr condition: No at the parting line part    -   Resin leakage: No at the lower closure mechanism part    -   Roller average outer diameter: φ 15.84 mm    -   Variation of the outer diameter: 20 μm

Example C-3

The spring mechanism was set such that the maximum value of the moldinner pressure was 100 kg/cm². Other conditions were the same as thoseof Examples C-1 and C-2.

Results were as follows.

-   -   Mold releasing load: 40 kg (No scratch at releasing)    -   Burr condition: No at the parting line part    -   Resin leakage: No at the lower closure mechanism part    -   Roller average outer diameter: φ 15.88 mm    -   Variation of the outer diameter: 18 μm

Comparative Example C-1

The spring mechanism was set such that the maximum value of the moldinner pressure was 150 kg/cm². Other conditions were the same as thoseof Examples C-1 and C-2.

Results were as follows.

-   Mold releasing load: 100 kg (Rubbed scratch on surface)-   Burr condition: Present at the parting line part-   Resin leakage: Present at the lower closure mechanism part-   Roller average outer diameter: φ 5.93 mm-   Variation of the outer diameter: 18 μm

Comparative Example C-2

The inner pressure adjusting mechanism provided at the upper coresupporting member was taken off, and the resin was hot-set under thecondition of opening the narrow hole communicating the spare room withthe roller forming space. Other conditions were the same as those of theabove Examples. Results were as follows.

-   Mold releasing load: 18 kg (Rubbed scratch on surface)-   Burr condition: Present at the parting line part-   Resin leakage: Present at the lower closure mechanism part-   External appearance: Void occurring-   Roller average outer diameter: 015.68 mm-   Variation of the outer diameter: 50 μm

Comparative Example C-3

The inner pressure adjusting mechanism provided at the upper coresupporting member was taken off, and the resin was hot-set under thecondition of plug-stopping the narrow hole communicating the spare roomwith the roller forming space. Other conditions were the same as thoseof the above Examples. Results were as follows.

-   -   Mold releasing load: 140 kg (Rubbed scratch on surface)    -   Burr condition: Present at the parting line part    -   Resin leakage: Present at the lower closure mechanism part    -   Roller average outer diameter: φ 15.96 mm    -   Variation of the outer diameter: 18 μm

Example C-4

The roller of the center diameter of the core body being φ 12 mm wasused. Other conditions were the same as those of Example C-2. Resultswere as follows.

-   -   Mold releasing load: 40 kg (No scratch)    -   Burr condition: No at the parting line part    -   Resin leakage: No at the lower closure mechanism part    -   Roller average outer diameter: φ 15.00 mm    -   Variation of the outer diameter: 18 μm

Comparative Example C-4

The roller of the center diameter of the core body being φ 12 mm wasused. Other conditions were the same as those of Example C-2. Resultswere as follows.

-   -   Mold releasing load: 100 kg (Rubbed scratch)    -   Burr condition: No at the parting line part    -   Resin leakage: No at the lower closure mechanism part    -   Roller average outer diameter: φ 15.00 mm    -   Variation of the outer diameter: 14 μm

From the above mentioned results, the following is seen.

If adjusting the mold inner pressure to be 100 kg/cm² or lower, it ispossible to avoid almost perfectly the burr occurrence at the partingline part or the resin leakage from the lower closure mechanism part.The product can be released from the mold at low load without causingscratches at releasing.

On the other hand, if the mold inner pressure exceeds 100 kg/cm², burrsoccur and the resin leaks from the lower closure mechanism part.Besides, the mold releasing load is large, and badness appears byreleasing the mold as scratches remain. This face is applicable to evenif the elastic layers are different in thickness, and it has been foundthat if the elastic layer is smaller than 1 mm, the mold releasing loadis large, even if the mold inner pressure is lower than 100 kg/cm², andscratches at releasing the mold remain. From these occasions, forcarrying out the roll formation of easily releasing from the moldwithout creating scratches and burrs, it has been confirmed that themold inner pressure at hot-setting is adjusted to be 100 kg/cm² orlower, and the inner diameter D and the outer diameter d of thecylindrical metal mold are selected such that the thickness of theelastic layer is 1 mm or more.

In the invention equipping the core supporting member with the moldinner pressure adjusting mechanism, as the mold inner pressure athot-setting can be adjusted, various defects caused by excessive innerpressure can be prevented. In particular, if hot-setting by adjustingthe mold inner pressure to be 100 kg/cm² or lower, the resin leakage canbe avoided at the parting line part between the cylindrical metal moldand the core supporting member or the lower closure mechanism part, andproducts without burrs, so that it is possible to largely reduce asecondary process as the burr removal or the adhered resin removal fromthe mold after producing rollers. Further, since products can bereleased from the metal mold at low load, it is not necessary to coatthe mold releasing agent to the inside the cylindrical metal mold, andno scratches occur by releasing from the mold. Besides, as the moldinner pressure is 100 kg/cm² or lower, pressure proof required to themetal mold may be low, and such a metal mold having thin thickness andweight light structure can be used, and a cooling for a long time is notnecessary for heightening the property of releasing from the mold, sothat productivity is increased.

EMBODIMENT 7

FIG. 11 is a schematically structured view for explaining the rollerproducing method using the thermosetting liquid resin and the producingapparatus of the invention. The exemplified roller producing apparatus101 is equipped with a container 102A storing the thermosetting liquidresin containing a catalyst (called as “A liquid” hereafter), acontainer 102B storing the thermosetting liquid resin containing a crosslinking agent (called as “B liquid” hereafter), an injecting device 103having a measuring mechanism for measuring these thermosetting liquidresins, a mixing mechanism 104 for mixing both thermosetting liquidresins, a roller forming metal mold filled with the mixed resin into aninside forming space 106 a via a resin injecting 105, and transferringpipes 107A, 107B connecting between the containers and devices forpassing the liquid resin. Herein, the respective liquid resins in thecontainers 102A, 102B are added with a conductivity giving agent, andthe containers 102A, 102B are furnished with force feed pumps 108A, 108Bfor forcing to feed the respective liquid resins to the transferringpipes 107A, 107B. The injecting device 103 is also equipped withtemperature adjusting means 109A, 109A, . . . 109B, 109B . . . foradjusting the thermosetting liquid resin to be at desired temperatures.There is not provided a cooling mechanism for cooling the liquid resinas the prior art.

Sequence for producing the elastic roller of the invention by means ofthe above structure of the apparatus will be explained in detail.

At first, as the thermosetting liquid resin, the A liquid added with thecatalyst and the conductivity giving agent in a base polymer (mainagent) and the B liquid added with the cross linking agent and theconductivity giving agent in a base polymer (main agent) are prepared,measured respectively and stored in the container 102A and the container102B. For these containers 102A, 102B, pale cans on the market arestandardized, cheap, much available, and convenient. The liquid A andthe liquid B are de-foamed in vacuum, agitated, mixed and stored. As anagitation de-foaming mechanism, generally the containers 102A, 102B areattached to a turn table and rotated to agitate with agitating vaneswhile reducing pressure by a vacuum pump.

The thus prepared A liquid and B liquid are forcibly sent to theinjection device 103 through the transferring pipes 107A, 107B as aflexible hose, and measured to be desired weight by respective cylinders111A, 111B. Next, the measured liquid resins in the cylinders go forwardthrough screws 112A, 112B and are jetted, pass through the resininjecting 106 b of the metal mold 106 from the injecting nozzle 105 asbeing mixed by the mixer 104, and are filled into the cavity composingthe roller forming space 106 a. The mixing mechanism 104 makes noespecial limitation if enabling to stand and mix against the jettingpressure of the liquid resin, and ordinarily, either of a dynamic mixerand a static mixer is served. The static mixer has a structure providedwith the mixing vanes having a plurality of spirally twisted continuouselements at the inside space of the mixing mechanism, divides a fluidrunning in the inside space into two parts by means of the mixing vanes,and jets it out. The dynamic mixer has a mixing rotor rotating screws orgears in the inside space of the mixing mechanism, mixes uniformly thefluid running in the inside space by means of the mixing rotor, and jetsit out.

In the range from the raw material containers 102A, 102B to theinjecting device 103, as the liquid resin is divided in the A liquid andthe B liquid, the cross linking reaction does not occur, so that acooling procedure as the conventional technical knowledge for coolingthe thermosetting liquid resin is unnecessary. Both liquids are mixed inthe mixing mechanism 104, and since at the same time as mixing, themixed resin is continuously jetted at high pressure into the formingspace 106 s of the roller forming metal mold 106, the liquid resin isscarcely adhered and solidified to the inside wall faces of the mixingmechanism 104 or the pouring nozzle 105. That is, the liquid resin inthe mixing mechanism 104 is periodically replaced by continuouslyforming, so that the liquid resin does not stay in the mixing mechanismfor a long period of time and is hardly solidified by the cross linkingreaction. Thus, the cooling procedure necessary in the prior art isunnecessary, thereby enabling to accomplish a low cost of a facility.

For avoiding the cross linking reaction of the mixed liquid in the rangefrom the mixing mechanism 104 to the pouring nozzle 105, temperatures ofthe liquid resin at injecting is set to be 20 to 70° C., preferably 20to 60° C. Therefore, the heaters 109A, 109A, . . . 109B, 109B . . . arearranged around the cylinders 111A, 111B. If heating the liquid resinexceedingly 60° C., the cross linking reaction gradually progresses, theresin component is solidified and accumulated on the wall in the mixingmechanism, and the mixing efficiency goes down and the quality is muchprobably varied.

In addition, the viscosity of the base polymer of the liquid resin isadjusted, or the liquid resin before pouring is heated by thetemperature adjusting means for preferably adjusting the viscosity ofthe liquid resin at injecting to be 5000 poises or lower. If pouring theliquid resin of the viscosity exceeding 5000 poises, the pressureeffecting to the metal mold becomes high and the structure of the metalmold should be thick, and for decreasing said pressure, the pouring timeof the liquid resin should be extended, and further at pouring, an airwithin the cavity is easily involved into the pouring and the number ofpouring holes must be increased.

As is seen, in the invention, the liquid resin is not adhered norsolidified to the transferring pipes 107A, 107B, the cylinders 111A,111B, the mixing mechanism 104 and the pouring nozzle 105, so that thefrequency and necessity of dissembling to clean the apparatus areextremely decreased. As the liquid resin of low viscosity can beinjected at temperatures near a room temperature, it is not necessary tomake the thick structure of the roller forming metal mold 106, and whenhot-setting the liquid resin injected to the forming space 106 a, theheating load is not increased and the hardening reaction is sufficientwith a short time, so that a producing cycle is remarkably heightened.Practically, a main maintenance is enough to only the mixing mechanism,and such merits appear that the frequency and labor therefor areconsiderably reduced.

Besides, in the invention, being different from the liquid resin of theexisting one liquid, there is little risk of increasing viscosity by thecross linking reaction of the liquid resin in the container.

Next, the base polymers to be used to the A liquid and the B liquid arecomponents hardening by making hydrosilyl with the cross linking agent.Specifically, since the base polymer has at least one alkenyl group inmolecule, the hydrosilyl reaction occurs and becomes a high molecularcondition and is hardened, and a repeating unit composing a main chainis polymer mainly comprising oxy alkylene unit or saturated hydrocarbonunit, for example, a silicone based addition reacting typed liquid resinis a typical example thereof. The number of alkenyl group in the basepolymer should be at least one for the hydrosilyl reaction with thecross linking reaction, and from the viewpoint of obtaining good rubberelasticity, in a case of molecule in a straight chain, two alkenylgroups are placed at both terminals of molecule, and in a case ofmolecule having branches, it is desirable that two or more alkenylgroups are placed at both terminals of molecule.

In a case that the repeating unit composing the main chain is polymermainly comprising oxy alkylene unit or saturated hydrocarbon unit, if asmall amount of the conductivity giving agent is added, volumeresistivity of 104 to 1012 Ωcm favorable to the roller is available.

Herein, oxyalkylene based polymer is meant by such polymer containing 30wt % or more oxyalkylene unit among units composing the main chain,preferably 50 wt % or more, and as a starting material when makingpolymer for composing a remainder excepting oxyalkylene unit, compoundcontaining two or more of active hydrogen, for example, ethylene glycol,bisphenol based compound, glycerine, trimethylol propane,pentaerythritol are taken up.

On the other hand, if the repeating unit composing the main chain insaid base polymers is polymer comprising saturated hydrocarbon unit, ithas a low water absorption rate and is preferable for obtaining rollerssmall in environmental variation of electric resistance. This polymer isalso a component of making hydrosilyl reaction with the cross linkingagent similarly to the above mentioned oxyalkylene based polymer andbecoming hardened, and a component becoming high molecule by causinghydrosilyl reaction owing to alkenyl group existing in molecule andhardened. Actually exemplified are isobutylene based polymer,hydroisobutykene based polymer, or hydrobutadiene. These polymers maycontain the repeating units of other components such as copolymer, andit is important for not spoiling the characteristics of obtaining therollers having a low water absorption rate and being small inenvironmental variation of electric resistance to contain saturatedhydrocarbon unit 50 wt % or more, preferably 70 wt % or more.

The components contained in the cross linking agent are sufficient withcompounds having at least two hydrosilyl group in molecule, and if thenumber of hydrosilyl group contained in molecule is too much, hydrosilylgroup easily much remains in hardened substances to cause voids orcracks, and so it is preferable to adjust the number to be 50 or less,more preferably 2 to 30 from the viewpoint of controlling rubberelasticity of the hardened substances and making storing stabilityfavorable. In the invention, having one of hydrosilyl group is meant byhaving one of H to be combined with Si. Therefore, in a case of SiH₂,hydrokysillyl is two, but if H to be combined with Si is combined withdifferent Si, such combination is preferable from viewpoint ofhardenability and the rubber elasticity.

The molecular amount of the cross linking agent is preferably adjustedto be 30,000 or less in number average molecular amount (Mn) from theviewpoint of making workability of product rollers good, more preferably300 to 15,000 in Mn from the viewpoint of reactivity or compatibilitywith said base polymer.

As to the cross linking agent, considering that cohesive force is largerthan that of the cross linking agent, it is important in thecompatibility to have modification containing phenyl group, and in aneasy availability, styrene modification is suited, and in a storingstability, α-methyl styrene is suited.

The above catalyst is enough if it can be used as a hydro sillylcatalyst, and is not especially limited. As to the using amount of thecatalyst, 10-8 to 10-1 mol, further 10-8 to 10-6 mol per 1 mol of thealkenyl group in base polymer (main agent) component are preferable fromthe viewpoint of avoiding check of hardening by catalyst poisoning andgood balancing between appropriate pot life and low cost. As thesecatalysts, for example, enumerated are platinum simplex, catalystcausing simplex as alumina to carry platinum, chloro platinic acid(including complex as alcohol), complex of platinum, metallic chloridesof rhodium, ruthenium, iron, aluminum, titanium. Among them, in thepoint of catalytic activity, preferable are chloro platinic acid,platinum olfin complex, platinum vinyl siloxane complex. The catalystmay be used sole or co-used two kinds or more.

If using conductive composition added with conductivity giving agent inthe above mentioned resin compositions, such rollers are produced whichare suited as rollers functioning for electrophotography. As theconductivity giving agent, carbon black is good. The conductivity givingagent is in advance mixed with base polymer by means of a roll mixer,and the mixture is added respectively to the A liquid and the B liquidsuch that the cross linking reaction moderately when both liquids aremeasured 1:1. Practically, in each solution, preferably the conductivitygiving agent is 1 to 35 wt % added to base polymer, and added at thesame amount to the A liquid and the B liquid to provide viscosity atsubstantially the same level. This is why if both liquids areconsiderably different in the viscosity, the mixing efficiency goes downand the crossing linking reaction is less to advance. For example, ifadding the conductivity giving agent to only the A liquid or the Bliquid, the adding amount is about 40 wt % to largely bring up theviscosity of one side liquid, so that the mixing efficiency isremarkably lowered.

To the above mentioned resin composition, a filler, a preservationstabilizing agent, a plasticizer, an ultraviolet absorbing agent, alubricant and a pigment may be added appropriately.

The thermosetting liquid resin injected into the roller forming metalmold 106 is heated to generate the cross-linking reaction, hardened andis formed to agree with the shape of the roller forming space 106 a intosuch as cylindrical form. At both ends in the axial direction of theroller main part as the product, the supporting shafts are formed forattaching to bearings of the electrophotographic apparatus. Thesupporting shaft is formed by penetrating or disposing the shaft bodycomposed of a stainless steel or an iron in an axis of the cylindricalroller, otherwise forcing, adhering or pinning the shaft body in anattaching hole formed in the axes of both ends of the main body.

As mentioned above, according to the roller producing method and theapparatus thereof using the thermosetting liquid resin of the invention,the roller forming metal mold is prepared, the thermosetting liquidresin containing the cross linking agent and the thermosetting liquidresin containing the catalyst are separately stored in the respectivecontainers, measured to be predetermined amounts, injected into theroller forming space while both thermosetting liquid resins are beingmixed in the mixing mechanism, and hot-set to form the main body, andtherefore, (1) until being injected into the roller forming space, thethermosetting liquid resin is not caused with the cross linkingreaction, and since the liquid resin is not adhered nor solidified tothe inside walls of the transferring pipes and the cylinders, and thepouring nozzle 105, the frequency and necessity of disassembling toclean the apparatus are extremely decreased, and (2) since the coolingprocedure of the liquid resin is not required until the injection, andthe liquid resin of low viscosity can be injected at temperatures near aroom temperature, it is not necessary to make the thick structure of theroller forming metal mold 106, and when hot-setting, the heating load isnot increased and the hardening reaction is sufficient with a shorttime, so that a producing cycle is remarkably heightened and theproduction cycle is markedly improved, and the cost-down is possible byunnecessary facility of the cooling mechanism.

By the temperature adjusting instrument, the temperature of thethermosetting liquid resin at injection is adjusted to be 20 to 70° C.,thereby enabling to securely prevent the liquid resin fromsolidification.

EMBODIMENT 8

With reference to FIGS. 12 to 14, explanation will be made to theembodiment of the injection forming apparatus according to theinvention. FIG. 12A is a plan view of the apparatus of the invention andB is a bottom view thereof. FIG. 13 is a schematic view showing the sideview of the apparatus (the cross sectional view A—A of FIG. 12A) FIG. 14is enlarged cross sectional views of elementary parts of the presentapparatus.

The injection forming apparatus 301 of this embodiment is composed ofthe cylindrical metal mold 304 inserted inside with an alloy-made corebody 303, the injection forming metal mold 302 composed of the coresupporting members 305, 306 fitted inside to both edge parts in theaxial direction of the cylindrical metal mold 304 as holding both edges303 a, 303 b of the inside inserted core body 303, and the heatingmechanisms 307, 308 disposed around the injection forming metal mold 302and holding said metal mold 302 at both sides in the diameter direction.Further, the inside of the cylindrical metal mold 304, the core mainpart 303 c and the core supporting members 305, 306 form the rollerforming space 317 for introducing the resin material.

Both ends 303 a, 303 b of the core body 303 are set and held in coresupporting holes 305 a, 305 b formed in the core supporting members 30,306. In this embodiment, the core body 303 has steps between both ends303 a, 303 b to be fitted in the core supporting holes 305 a, 306 a andthe core main body 303 c, but is not limited thereto, and a straighttype without steps is enough.

The cylindrical metal mold 304 is shaped in seamless pipe, and theinside face is preferably performed with fluorine resin coating orelectroless plating from the viewpoint of releasing products from themold. The upper and lower core supporting members 305, 306 have almostthe same outer diameter as that of the cylindrical metal mold 304, andthe lower core supporting member 306 is formed with a resin injectinginlet 306 b for filling the resin material in the roller forming space317, while the upper core supporting member 305 is formed with a gasventing hole 305 b for releasing gas pressure effected by the filledresin. As shown in FIG. 14A, at the lower end of the core supportingmember 305, a fitting projection 305 c is formed for fitting inside thecylindrical metal mold 304, and as shown in FIG. 14B, also at the upperend of the core supporting member 306, a fitting projection 306 c isformed for fitting inside the cylindrical metal mold 304, a so-calledfaucet structure is adopted. At outer circumferences of the respectiveedges 305 d, 306 d of the upper and lower core supporting members 305,306, for tightening the upper and lower core supporting members 305, 306to the cylindrical metal mold 304 with sufficient force, 1st obliquefaces 305 e, 306 e are defined in ring shape which are determined inangle to be within ranges of 5 to 30°, more preferably 5 to 20° withrespect to the axially vertical direction of the metal mold.

The heating mechanism 307, 308 are divided into left and right twoparts, and are inside equipped with heat generators such as cartridgeheaters, hand heaters, high frequency induction heaters and heatingmedium circulators, and the inner wall faces thereof are contacted tothe outer face of the cylindrical metal mold 304 for heat transfer tothe cylindrical metal mold 304. Preferably, the radius of curvature ofthe inner wall faces of the cylindrical metal mold 304 is set to be halfor somewhat larger than this half of the outer diameter 304, and amaterial quality of the inner wall face preferably has substantially thesame thermal expansion coefficient as that of the cylindrical metal mold304. At both ends in the axial direction of the heating mechanisms 307,308, pawl members 313, 314, 315, 316 are provided in a manner of holdingthe edges 305 d, 306 d at the outer circumferences of the coresupporting members 305, 306 between left and right both sides, and thesepawl members 313, 314, 315, 316 are formed inside with band-shaped 2ndoblique faces 313 a, 314 a, 315 a, 316 a. Besides, the respective 2ndoblique faces 313 a, 314 a, 315 a, 316 a are pasted with band-shapedheat resistant elastic members 309, 310, 311, 312, and 2nd oblique facesare forced to contact these heat resistant elastic members to press the1st oblique faces 305 e, 306 e. The pawl members 313, 314, 315, 316 maybe secured to the heating mechanism main bodies by means of welding orbolt tightening, or moving mechanisms (not shown) may be provided forsliding the pawl members solely in the diameter direction.

A sequence for producing the roller by use of the above mentionedinjection forming apparatus will be explained in detail. At first, thecore body 303 is inserted inside the cylindrical metal mold 304, bothends 303 a, 303 b are fitted into the core body holding holes 305 a, 306a defined in the core supporting members 305, 306, and these coresupporting members 305, 306 are inserted in both end parts of thecylindrical metal mold 304 so as to form the roller forming space 317inside of the injection forming metal mold 302. Under this condition,the heating mechanisms 307, 308 are moved from left and right both sidesin a manner of holding the injection forming metal mold 302therebetween, to cause the 2nd oblique faces 313 a, 314 a, 315 a, 316 aformed in the pawl members 313, 314, 315, 316 to contact the heatresistant elastic members 309, 310, 311, 312 so as to press the 1stoblique 305 e, 306 e, so that the core supporting members 305, 306 aresecured to the cylindrical metal mold 304. By securing the heatingmechanisms 307, 308, the upper and lower core supporting members 305,306 are firmly held at both edge faces 305 d, 306 d, and the injectionforming metal mold 302 is tightened and held. For firmly tightening thecylindrical metal mold 304 to the core supporting members 305, 306, atightening load of about 20 kgf or higher is ordinarily necessary, andthe invention can easily accomplish it.

Next, the lower core supporting member 306 is provided at the resininjecting inlet 306 with the resin injecting nozzle (not shown) forinjecting and filling the resin material in the roller forming space317. The gas pressure then generated inside is released by opening thegas venting hole 305 b. After completing to charge the resin material,the gas venting hole 305 b is closed as needed, and subsequently theroller forming space 317 is heated around 60 to 150° C. by the heatgenerators furnished in the heating mechanisms 307, 308 for hot-settingthe resin material. The inner diameter of the gas venting hole 305 b ispreferably adjusted to be 0.5 to 3.0 mm. Being less than 0.5 mm, theresin leaks due to an inner high pressure to probably create burrs inproducts, while being more than 3.0 mm, the resin invades in the gasventing hole and widens an adhering area in the inner wall of the metalmold, so that it is difficult to release products from the mold.

The injection forming metal mold 302 is cooled and released under acondition where the heating mechanisms 307, 308 are moved left and rightin the diameter direction and is opened. Then, the core supportingmembers 305, 306 are taken out, and after releasing the roller as aproduct of the invention, the above mentioned sequence is again repeatedto produce new products.

At hot-setting, since the cylindrical metal mold 304 and the upper andlower core supporting members 305, 306 are thermally expanded, surfacepressure becomes gradually higher between the 1st oblique faces 305 e,306 e formed in the upper and lower core supporting members 305, 306 andthe 2dn oblique faces 313 a, 314 a, 415 a 316 formed in the respectivepawl members 313, 314, 315, 316, and the tightening load becomes largerbetween the cylindrical metal mold 304 and the upper and lower coresupporting members 305, 306, but in this embodiment, since the heatresistant elastic members 309, 310, 311, 312 are interposed between the1st oblique faces 305 e, 306 e and the 2nd oblique faces 313 a, 314 a,415 a 316, an increasing part of the tightening load generated by thethermal expansion is absorbed thereby, so that excessive load is notadded to the core body 303, deformation as buckling is prevented, andthe air tightness is heightened in the roller forming space, and theroller formability is prevented from spoiling. The thickness of the heatresistant elastic members 309, 310, 311, 312 is suitably 0.5 to 5.0 mm,and as the material quality having moderate elasticity at said heatingtemperature of 60 to 150° C., silicone or fluoro-rubber are suited.

As the resin materials of the products, it is possible to use themixture of one or two kinds or more of the thermosetting liquid resinsuch as epoxy resin, phenol resin, urea resin, melamine resin, franresin, unsaturated polyester resin, and polyimide resin, or siliconebased thermosetting liquid resin.

In the above embodiment, the resin injecting inlet 306 b is defined inthe lower core supporting member 306, and the gas venting hole 305 isdefined in the upper core supporting member 305, and instead therefor,as schematically shown in FIG. 15, it is sufficient to form apenetrating hole 318 in an upper core supporting member 305′ whichserves as the resin injecting inlet and the gas venting hole. Namely,when the resin injecting nozzle 319 is inserted in the penetrating hole318, the resin material is injected and filled in the roller formingspace 317 under a condition of providing a space for venting the gasbetween the resin injecting nozzle 319 and the penetrating hole 318. Ifadopting such a structure, the solidified resin material is less to clogthe resin injecting inlet, so that a merit is obtained which makes themaintenance work of the forming device easier.

EMBODIMENT 9

Explanation will be made another embodiment of the injection formingapparatus according to he invention.

FIGS. 16 to 18 are schematically structured views showing thisembodiment. FIG. 16A is a plan view of this apparatus and FIG. 16B is abottom view thereof. FIG. 17 is a schematically cross sectional viewshowing the side view of the apparatus (B—B cross sectional view of FIG.16A). FIG. 18 is enlarged cross sectional views of elementary parts ofthe apparatus.

The injection forming apparatus 321 of this embodiment is composed ofthe cylindrical metal mold 324 inserted inside with a core body 323, theinjection forming metal mold 322 composed of the core supporting members325, 326 fitted inside to both edge parts in the axial direction of thecylindrical metal mold 324 as holding both edges 323 a, 323 b of theinside inserted core body 323, and the heating mechanisms 327, 328disposed around the injection forming metal mold 322 and holding saidmetal mold 322 at both sides in the diameter direction.

At the lower end of the core supporting member 325 and the upper end ofthe core supporting member 326, fitting projections 325 c, 326 c areformed for fitting into both ends of the cylindrical metal mold 324similarly to the above embodiment 8, and the faucet structure isadopted. At the upper and lower core supporting members 325, 326, 1stbrims 325 f, 326 f are expanded on the outer circumferences respectivelyopposite to the cylindrical metal mold 324, while also at both ends ofthe cylindrical metal mold 324, 2nd brims 324 f, 324 g are expanded inopposition to the 1st brims 325 f, 326 f. As shown in the enlarged crosssectional views in FIG. 18, at the rear faces of the 1st brims 325 f,326 f and the 2nd brims 324 f, 324 g, 1st oblique faces 325 a, 326 a and324 a, 324 b are formed which tilt at predetermined angles with respectto the axially vertical direction. These tilting angles are preferablydetermined to be 5 to 30°, especially 5 to 20° for tightening the upperand lower core supporting members 325, 326 to the cylindrical metal mold324 with enough force.

On the other hand, the heating mechanisms 327, 328 are formed in theinner wall faces with tapered grooves 330, 331 in concave shape forengaging the 1st brims 325 f, 326 f and the 2nd brims 324 f, 324 g inopposition under a closing condition. In the upper and lower inner facesof these grooves 330, 331, 2nd oblique faces 330 a, 330 b, 331 a, 331 bare formed in half ring shape, and are pasted with half ring shaped heatresistant elastic members 332, 333, 334, 335. The 2nd oblique faces 330a, 330 b, 331 a, 331 b are urged to press upward and downward on theheat resistant elastic members 332, 333, 334, 335 so as to press the 1stoblique faces 325 a, 324 a and 326 a, 324 b and tighten the coresupporting members 325, 326 and the cylindrical metal mold 324. Othercomposing members are almost the same as those of the embodiment 8,excepting the pawl members and the 1st oblique face, and detailedexplanation will be omitted.

A sequence for producing the roller by use of the above mentionedinjection forming apparatus will be explained in detail. At first, thecore body 303 is inserted inside the cylindrical metal mold 324, bothends 323 a, 323 b are fitted into the core body holding holes 325 a, 326a defined in the core supporting members 325, 326, and these coresupporting members 325, 326 are inserted in both end parts of thecylindrical metal mold 324 and the injection forming metal mold 322 isclosed so as to form the roller forming space 336. Under this condition,the heating mechanisms 327, 328 are moved from left and right both sidesin the vertical direction in a manner of holding the injection formingmetal mold 322 therebetween, so that the brim parts 330, 331 are engagedwith the 1st brim parts 325 f, 326 f and the 2nd brim parts 234 f, 324g, and the 2nd oblique faces 330 a, 330 b, 331 a, 331 b are forced topress upward and downward the heat resistant elastic members 332, 333,334, 335 to press the 1st oblique faces 325 a, 326 a, 324 a, 234 b. Bytightening the heating mechanism, the core supporting members 325, 326and the cylindrical metal mold 324 are tightened and maintained.

By the same sequence as that of the embodiment 8, the roller formingspace 336 is injected and filled with the resin material, the injectionforming metal mold 322 is cooled, the heating mechanisms 327, 328 aremoved respectively left and right in the axial direction to make anopening condition, and the injection forming metal mold 322 is released.Subsequently, the core supporting members 325, 326 are taken out, andafter releasing the roller as a product of the invention, the abovementioned sequence is again repeated to produce new products.

In the above embodiments 8 and 9, the 1st oblique face and the 2ndoblique face corresponding thereto are provided to both ends of themetal mold, and in the invention, these faces may be provided to oneends.

In the above embodiments 8 and 9, the injection forming metal mold is avertical type but the invention does not limit thereto, a lateral typeor a combination of a lateral type and a vertical type are sufficient.

As mentioned above, according to the injection forming metal mold of theroller for the electrophotography, the core supporting member to befitted in both ends of the cylindrical metal mold has the 1st obliquitytilting at a fixed angle with respect to an axial and verticaldirections in the outer wall face, and the heating mechanism has aninner wall face contacting to hold the injection forming metal moldunder a condition of closing the heating mechanism and having the 2ndobliquity pressing the 1st obliquity to the inner wall face, whereby theinjection forming metal mold is tightened and held, so that thestructure of the metal mold is simplified, and it is possible to largelyautomatize a series of procedure from setting up of the injectionforming metal mold to the pouring, hot-setting, disassembling of themetal mold and releasing of the product from the mold, which have beendifficult in the prior art.

Further, the heat resistant elastic member is interposed between the 1stoblique face and the 2nd oblique face, so that the increasing part ofthe tightening load generated by the thermal expansion of the metal moldat hot-setting is absorbed by the heat resistant elastic member, andstable tightening force of the metal mold can be provided, and theroller formability can be heightened.

EMBODIMENT 10

Another embodiment of the invention will be explained, referring to thedrawings. As shown in FIG. 19A, the forming metal mold 400 has thecylindrical metal mold 13 and a pair of core supporting members 14 a, 14b disposed at both ends of the cylindrical metal mold 13, and thecylindrical metal mold 13 and the pair of core supporting members 14 a,14 b define the roller forming space 15. One of the core supportingmembers 14 b is provided with the resin injecting inlet 16. In theinside of the cylindrical metal mold 13, the core body 21 of the resinroller to be formed is held at both ends in the core supporting holes 17a, 17 b formed in both core supporting members 14 a, 14 b. The corebodies 21 of the resin roller are, for example, as shown in FIGS. 22A to22C. As materials of the core body 21, known arbitrary ones, forexample, metallic materials or resin materials rendered to be conductiveare applicable. As to sizes of the resin roller, not different fromthose of the existing resin rollers, generally, the diameter is 10 to 30mm and the length is 200 to 400 mm.

The cylindrical metal mold 13 and the core supporting members 14 a, 14 bare composed of known arbitrary materials for thermosetting liquidresin, preferably pre-hardened steel, quenched steel, non-magneticsteel, carbon tool steel, or corrosion resistant steel (stainlesssteel). In the invention, ring like concave grooves 430 are in advanceformed at the opening edges of the core supporting holes 17 a, 17 b ofthe core supporting members 14 a, 14 b for inserting the core body 21therein, such that the core supporting members 14 a, 14 b are, as theembodiment shown in FIG. 19, formed as the resin-formed edge faces standin arc along the core body 21 when forming, said ring like concavegrooves 430 reducing the diameter in arc toward an inner part of thecore supporting holes 21 of larger diameter than the outer diameter ofthe core supporting holes 21 supported by said core supporting members14 a, 14 b.

For forming the resin roller by means of the resin roller forminginjection forming 400, the core body 21 is inserted at both ends in thecore supporting holes 17 a, 17 a of the pair of core supporting members14 a, 14 b, and under a condition of previously holding the core body 21between both core supporting members 14 a, 14 b, the resin material ispoured and filled from the resin injecting inlet 16 into the rollerforming space 15 formed by the cylindrical metal mold 13 and the coresupporting members 14 a, 14 b of the cylindrical metal mold 13. Theresin poured and filled in the roller forming space 15 is also filled inthe ring like grooves 430, 430 formed in the core supporting members 14a, 14 b following the periphery of the core body 21 at the axial bothedge faces of the forming space 15. After pouring and filling the resinmaterial, by hot-setting the resin in the roller forming space 15, theresin-formed body 12 is formed cylindrically around the core body 12.The edge face 12 c of the cylindrical resin-formed body 12 is formed asstanding in the shapes of the ring like concave grooves 430 of the coresupporting members 14, and standing parts 440 are formed following thecore body 21. After completion of solidifying the resin, the coresupporting members 14 a, 14 b are taken out upward and downward from thecylindrical metal mold 13 in the axial direction. Subsequently, theformed product held within the cylindrical metal mold 13 is removedupward or downward in the axial direction by doing as pushing the core21 with respect to the cylindrical metal mold 13. FIG. 19B shows theformed product of the resin roller 10 taken out.

As the embodiment shown in FIG. 19, with respect to the shape of thestanding part 440 reducing the diameter in are following the end part ofthe core body 21, the radius of curvature R of the arc in the outer faceof the standing part reducing the diameter is preferably formed to be0.2 to 3 mm, and it is more preferable that the radius of curvature R ofthe arc is formed to be 0.5 to 2 mm, though depending on tolerance whenthe resin roller 10 is incorporated in an actual electro-photography.The standing size L in the axial direction of the core body 21 from theedge face 12 c of the resin-formed body is preferably 0.5 to 5 mm, morepreferably 1 to 3 mm.

EMBODIMENT 11

FIG. 20A shows a forming metal mold of another embodiment, and FIG. 20Bshows a shape of the formed product of the resin roller 10 by use ofthis forming metal mold 400. This forming metal mold 400 is formed withring like concave grooves 430, 430 in the core supporting members 14 a,14 b in such shapes that the standing parts 440 of the resin-formed body12 linearly reduce the diameter as going toward the ends of the corebody 21. With respect to the shape of the standing part 440 when formingthe standing part to linearly reduce the diameter toward the end part ofthe core 21 as the edge face 12 c of the resin-formed body follows thecore body 21, the standing size L in the axial direction of the corebody 21 from the edge face 12 c of the resin-formed body is preferably0.3 to 3 mm, more preferably 1 to 2 mm, though depending on tolerancewhen the resin roller is incorporated in an actual electrophotographicapparatus. The standing angle 0 is preferably 5 to 60° on the basis ofthe axial direction in the surface of the core body 21.

EMBODIMENT 12

FIG. 21A shows a further embodiment, in which a forming metal mold is toform stepwise standing parts 440 of the edge parts 12 c of theresin-formed body, and FIG. 21B shows the shape of the formed body ofthe resin roller obtained by the forming metal mold 400. As to the shapeof the stepwise standing part 440, the standing size L in the axialdirection of the core body 21 from the edge face 12 c of theresin-formed body is preferably 0.3 to 3 mm, more preferably 1 to 2 mm,though depending on tolerance when the resin roller is incorporated inan actual electrophotographic apparatus. The interface between thestepwise standing part 440 and the edge face 12 c of the resin-formedbody reduce the diameter in arc. As to the thickness of the stepwisestanding part 440, one step is enough as shown, and also two steps ormore are enough gradually reducing the diameter. The sizes are asmentioned above.

EMBODIMENT 13

Further, as other embodiments, standing parts 440 shown in FIGS. 23A to23G can be adopted depending on conditions in processing the coresupporting members or allowed shapes in actual machines. For example, ifnot permitting the stand of the formed resin from the edge part 12 c ofthe resin-formed body to the edge part of the core body 21 in dependenceon sizes of the electrophotographic apparatus, it is possible, forexample, as shown in FIGS. 23F and 23G, to design in ring like concaveshape the circumference of the core body 21 of the edge face 12 c of theresin-formed body, and form the standing part 440 in the concave part450. The sizes of the standing parts 440 shown in FIGS. 23A to 23G arethe same as those of the embodiments shown in FIGS. 19 to 21.

One example of the actually forming method of the inventive resin rollerwill be explained. For example, polysiloxane based hardening agent andthe conductivity giving agent (carbon black) are mixed in terminalallylated polyoxy propylene based polymer, and when the roller is formedof the outer diameter being φ 16 mm and the length of the resin-formedbody being 250 mm in the liquid resin injecting and pouring machine, theviscosity of the mixed and poured resin is 200 to 5000 poises throughdepending on the number of mixing parts of the conductivity givingagent, and the pouring pressure is 0.5 to 15 MPa. When, for example, thethickness of the resin-formed body is 4 mm in the roller of the abovesizes, the diameter of the resin injecting inlet is 1 to 2 mm. The metalmold stands vertically in the lengthwise direction, and preferably theresin is poured from the lower part of the metal mold.

The metal mold is heated by the existing arbitrary methods. For example,there are a heating method within the heating oven furnished withheating fans, a method of heating by arranging electric heaters aroundthe metal mold, or a method of arranging the induction heating coilsaround the metal mold. For temperatures of the metal mold, optionaltemperatures can be selected, enabling to pour the thermosetting liquidresin and hot-set the resin, and when pouring the resin, temperatureseasily pouring the resin and not solidifying it are preferable, forexample, 20 to 70° C. Further, the resin heating temperature isdesirably around 80 to 200° C., though depending on the amount ofhardening retardant.

As roller forming resin materials available to the inventive formingmethod, resins of heat-removal hardening are employed, for example,silicone, polyurethane, acrylonitrile.butadiene copolymer (NBR),ethylene.propylene.diene.methylen copolymer (EPDM). The thermosettingliquid resin may be added with other kinds of additives as needed. Forexample, if a resistance controlling agent as carbon is added, electricresistance of the roller can be controlled.

One of the preferable embodiments of the invention is to use thethermosetting liquid resin containing, as main components, (A) polymercontaining at least one alkenyl group in molecule and a repeating unitcomposing a main chain being mainly oxy alkylene unit or saturatedhydrocarbon unit, (B) a hardening agent containing at least twohydrosilyl group in molecule, (C) catalyst made hydrosilyl, and (D)conductivity giving agent. Since the forming resin comprising thereaction hardened substance of the hardening composition has especiallysoft structure, it displays enough elastic effect even if the thicknessis thin. When containing oxy alkylene unit, the resin is low inviscosity before hardening and easily handled, and on the other hand,when containing saturated hydrocarbon unit, the resin has the lowabsorption coefficient, and is desirable because the volume and theroller resistance are less to change.

The thermosetting liquid resin is added, if necessary, with materialsfor adjusting thermosetting reaction such as hardening agent, hardeningaccelerator, hardening retardant or others. Or, organic or inorganicfillers may be added. Further, some kinds of organic or inorganicpigments, thickener or mold releasing agent may be added.

In the following, explanation will be made to embodiments of theinvention, but the embodiments do not limit the invention.

The resin roller 10 of the roller outer diameter being φ 16 mm and thelength of a resin formed body 12 being 250 mm as shown in FIG. 19B wasformed by use of the metal mold 400 shown in FIG. 19A. The coresupporting members 14 a, 14 b of the forming metal mold 400 are definedwith the ring-like concave grooves 430, 430 such that the outer diameterd of the core body 21 is 8 mm, the shape of the standing part 440 at theedge face 12 c of the resin-formed body has the radius of curvature Rbeing 2 mm, and the standing size L of the core body 21 toward the axialdirection is 2.5 mm.

The used thermosetting liquid resin was 600 poises in the viscosity inthe mixed resin shown in the table 1.

In the liquid resin injecting and pouring machine, the mixed resinmaterial was poured into the metal mold having the resin injecting inlet16 of 1.5 mm from the lower portion under the pouring pressure of 4 MPa,the metal mold standing vertically in the lengthwise direction. Themetal mold was arranged within the heating oven provided with theheating fans and was heated by setting the atmospheric temperaturewithin the heating oven to be 140° C. for 20 minutes and releasing fromthe metal mold as exerting the leasing load of 20 kg in the axialdirection from the metal mold, and a formed product was obtained. As aresult, at the ends of the obtained roller, no resin leakage occurred.

In the resin roll and the forming metal mold of the invention, the edgeface of the resin-formed body stands along the core body, and sinceforce concentrating in the standing portion when releasing the moldafter forming is dispersed, the resin-formed body and the core body donot separate, and good products are available cheaply and stably.

INDUSTRIAL APPLICABILITY

The resin roller, the resin roller producing apparatus and the method ofproducing the same are suited to developing roller, charging roller,transcribing roller and others.

1. A method for producing a roller for an electrophoto graphic apparatuscomposed of a main body formed with a hardening type liquid resin andsupport rods for supporting both edges of the main body, characterizedby preparing a roller forming metal mold provided with a space forforming a roller main body as well as provided with a resin injectinginlet for filling the roller forming space with a hardening type liquidresin, storing separately a hardening type liquid resin containing across linking agent and a hardening type liquid resin containing acatalyst, respectively measuring set amounts thereof, mixing bothhardening liquid resins, and injecting the mixture of the liquid resinsinto the forming space from a resin pouring inlet so as to effect ahardening reaction for forming the roller main body.
 2. The method forproducing rollers with the hardening type liquid resin as set forth inclaim 1, wherein temperature of the hardening type liquid resin atinjecting is adjusted to be within a range of 20 to 70° C.
 3. The methodfor producing rollers with the hardening type liquid resin as set forthin claim 1 or 2, wherein viscosity of the hardening type liquid resin atinjecting is adjusted to be 5000 poise.
 4. The method for producingrollers with a hardening type liquid resin as set forth in claim 1 or 2,wherein the hardening type liquid resin containing the cross linkingagent and the other hardening type liquid resin containing the catalystare respectively combined with the same amount of conductivity givingagent.
 5. The method for producing rollers with the hardening typeliquid resin as set forth in claim 1 or 2, wherein the composition ofthe hardening type liquid resin has a polymer containing at least onealkenyl group per polymer chain and a main chain composed of repeatingunits being mainly oxy alkylene units or saturated hydrocarbon units,and the cross linking agent has at least two hydrosilyl groups permolecule.